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NON-TECHNICAL CHATS ON IRON AND STEEL 



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NON -TECHNICAL CHATS 
ON IRON AND STEEL 

AND THEIR APPLICATION TO 
MODERN INDUSTRY 

BY 

LaVERNE W. SPRING, A.B. 

CHIEF CHEMIST AND METALLURGIST, CRANE CO., CHICAGO 

WITH TWO HUNDRED AND NINETY-FOUR ILLUSTRATIONS AND DIAGRAMS 




NEW YORK 

FREDERICK A. STOKES COMPANY 

PUBLISHERS 



<5a 



Copyright, 1917, by 
Fredekick A. Stokes Company 



All rights reserved, including that of translation 
into foreign languages 



fi 



NOV -6 1917 



©CI.A'477438 
V4) \ \ 



■ nfO 



/^ 



TO 
MY FELLOW WORKERS 

IN THE VAST IRON AND STEEL INDUSTRY 

THIS BOOK IS 

AFFECTIONATELY DEDICATED 



FOREWORD 

It has long been a desire of the author to put into non- 
technical form the interesting data here given. During 
several years spent in the service of one of the great steel 
companies of this country, first in the laboratories and 
afterward in the rolling mills, he acquired a love for the 
industry that is now of fairly long standing. Spending as 
much of his spare time then and since in visiting various 
parts of that mammoth plant and as many others as he was 
able, he has always felt that this extremely interesting sub- 
ject could not fail to prove fascinating even to those who 
had previously known little of the manufacture of steel 
and steel products. Later work with gray and malleable 
cast irons and with cast steel enlarged the outlook and fur- 
ther urged his sharing these interesting things with others 
not so fortunately situated. 

Such an inspiration, if it may so be called, is the reason 
for the appearance of these articles. Practically as here 
reprinted, the first thirteen of them were published during 
1915 and 1916 in serial form in the "Valve World," the 
house organ of Crane Company of Chicago, with which the 
writer for some time has been connected. The enthusiasm 
with which they were received has been very gratifying, 
while the scores of letters bearing favorable comment tes- 
tify to the correctness of the judgment that the metallurgy 
of our most useful metal, iron, is of very general interest. 

It may be remarked by some that certain of the state- 
ments made in the book are not strictly accurate in that 
few details have been stated or exceptions made. This is 



viii FOEEWORD 

true, but it seemed necessary if main facts were to be made 
to stand forth with the boldness required to accomplish the 
purpose which the author had in mind. The chapters are 
in no way intended to be an encyclopedia of the subject. 
The idea, throughout has been to present only the main 
points and to show the derivation of the products from the 
raw materials and their relationships to each other. In 
other words the book is intended only as a sort of out- 
line. References are given which will aid in the selection 
of works to be consulted by any who are sufficiently inter- 
ested to go farther. 

Without the encouragement and cooperation of Crane 
Company and the kind assistance of friends, some within 
and some without the iron and steel industry, this little 
book would not have been possible. Special mention must 
be made of the aid given by Messrs. I. M. Bregowsky, J. A. 
Matthews, C. D. Carpenter, and others whose reading of 
and suggestions concerning parts of the manuscript were 
of much help. Thanks are due also to many individuals 
and firms for their very hearty cooperation in furnishing 
information and the photographs which appear in the pages 
of the book. 

L. W. S. 



Illustrations are from the following sources : 

A. M. Byers Co., Pittsburg. — National Tube Co., Pittsburg. — U. S. 
Steel Corporation, New York. — Tennessee Coal, Iron & Eailroad Co., Bir- 
mingham, Ala. — Shenango Furnace Co., Pittsburg. — Pickands, Mather & Co., 
Pittsburg. — United States Geological Survey. — Wellman-Seaver-Morgan Co., 
Cleveland, O. — Lackawanna Steel Co., Buffalo. — Cleveland-Cliffs Iron Co., Ish- 
peming, Mich. — J. H. Hillman & Sons Co., Pittsburg. — Harbison-Walker Be- 
fractories Co., Pittsburg. — By-Products Coke Corporation, Chicago. — H. Kop- 
pers Co., Pittsburg. — Federal Furnace Co., Chicago. — Crucible Steel Company 
of America, Pittsburg. — Crane Co., Chicago. — Interstate Iron & Steel Co., 
Chicago. — LaBelle Iron Works, Steubenville, O. — Morgan Construction Com- 
pany, Worcester, Mass. — J. A. Matthews, Syracuse, N. Y. — McLain's System, 
Milwaukee, Wis. — Allis-Chalmers Co., Milwaukee, Wis. — J. H. Williams & Co., 
New York. — Griffin Wheel Co., Chicago. — U. S. Molding Machine Co., Cleve- 
land. — Bradley Manufacturing Co., Bradley, 111. (Sears, Koebuck & Co., Chi- 
cago). — Snyder Electric Furnace Co., Chicago. — Commonwealth Steel Co., St. 
Louis. — John A. Crowley & Co., Detroit. — Illinois Steel Co., Chicago. — Pick- 
ands, Brown & Co., Chicago. — ' ' Sketches of Creation, ' ' by Alexander Win- 
chell. Harper & Bros., New York. — ' ' Descriptive Metallurgy of Iron, ' ' by 
S. Groves. — "Materials of Engineering," by E. H. Thurston. John Wiley & 
Sons, New York. — "Chambers' Encyclopedia." J. B. Lippincott, Philadel- 
phia. — ' ' Cast Iron in the Light of Eecent Eesearch, ' ' by W. H. Hatfield. 
Charles Griffin & Co., Ltd., London. — ' ' Handbook of Chemical Technology, ' ' 
Wagner-Crookes. D. Appleton & Co., New York. — "The Ore Deposits of the 
United States and Canada," by J. F. Kemp. McGraw-Hill Book Co., New 
York.—' ' The Valve World. ' ' Crane Co., Chicago.—' ' The Eomance of Steel, ' ' 
by H. Casson. A. S. Barnes & Co., New York.— "The Metallurgy of Steel," 
by Harbord & Hall. Chas. Griffin & Co., Ltd., London.— " Metallurgy of 
Steel," by H. M. Howe. McGraw-Hill Book Co., New York. — Tomlinson's 
"Encyclopedia of Useful Arts" (1854). G. Virtue & Co., New York — 
"Liquid Steel," by E. G. Carnegie. Longmans, Green & Co., New York. — 
"Iron and Steel in All Ages," by James Swank. American Iron & Steel 
Association, Philadelphia. — "The A.B.C. of Iron and Steel." Penton Pub- 
lishing Co., Cleveland, O. — "The Iron Age." David Williams, New York.— 
"The Iron Trade Eeview. " Penton Publishing Co., Cleveland, 0. — "High 
Speed Steel," by 0. Becker. McGraw-Hill Book Co., New York. 




CONTENTS 




I The Early History of Iron 

II The Raw Materials . 

III Raw Materials (Continued) 

IV The Blast Furnace . 
V A General Glimpse Ahead 

VI Wrought Iron .... 

VII Cementation and Crucible Steels 

VIII Bessemer Steel 

IX The Open-Hearth Process 

X Cast Iron .... 

XI Cast Iron (Continued) 

XII Malleable Cast Iron 

XIII Cast Steel .... 

XIV The Alloy Steels 
XV The High-Speed Steels 

XVI The Mechanical Treatment op Steel 

XVII The Rolling Process 

XVIII The Rolling op Rods 

XIX Wire and Wire Drawing . 

XX The Manufacture of Pipe and Tubes 

XXI The Manufacture of Seamless Steel Tubes 

XXII Transformations and Structures of the Steels 

XXIII The Equilibrium Diagram of the Iron Carbon 

Alloys ........ 

References ....... 

Index ........ 



1 

17 

37 

52 

69 

91 

106 

123 

142 

160 

178 

195 

214 

233 

240 

245 

259 

277 

284 

292 

302 

310 

335 
350 
355 



NON-TECHNICAL CHATS ON IRON AND STEEL 



CHAPTER I 



THE EARLY HISTORY OF IRON 



When in imagination we see the iron maker of early 
clays sitting cross-legged on his platform between two 
crude bellows formed from goat skins with slits for 
air intakes and nozzles of bamboo, working them alter- 
nately to deliver their pitifully small streams of air 
into the hole 
in the side of 
a bank of clay 
which served 
as a furnace, 
we wonder at 
his patience ; 
and after long 
hours of such 
effort his re- 
ward was only 
a few pounds 
of iron! 

Contrast with this, if you please, the modern blast furnace 
with its towering height of 100 feet, its four huge heating 
stoves, the big blowing engines which each minute deliver to 
the furnace 50,000 cubic feet of blast, and the whole array 
of dust arresters, gas washers, and automatic ore and coke 
handling machinery which are essentials of this king of 
modern metallurgical devices. How insignificant seems the 

1 




Prehistoric Man 



2 NON-TECHNICAL CHATS ON IRON AND STEEL 

output of the ancient furnace when compared with the 
daily yield of 500 tons from this giant of to-day ! 
How has this come about? 

Looking back over the centuries we see a period many 
thousands of years ago when primitive man lived in caves 
or other rude habitations and was entirely without the 
implements which we now consider indispensable. The 
weapons with which he defended his wife and babes from 
the wild beasts and from his warlike neighbors were 
clubs, wooden spears with perhaps a bone or shell tip, and 
hatchets of chipped stone tied with thongs of hide into a 
split stick. He managed by ingenious snares and his crude 
weapons to provide game and fish for 
the support of his family. 

He did not shave often, for his wife 
was not as particular in regard to his 
appearance as are modern women, but 

The First Razor wllen SUCh a thill & happened, a piece of 

shell was his razor. The good wife had 
no steel needles with which to sew together skins for their 
crude clothing. If she darned her husband's socks it is 
not recorded, nor did she use steel crochet hooks in making 
the "doilies" for their parlor table. 

When grain began to supplement the wild game, fruit, 
and berry diet, it was broken between flat stones or ground 
in stone mortars. Fires were kindled after long and labori- 
ous twirling or rubbing together of two dry pieces of wood. 
With his stone hatchets and by liberal burning away of 
parts by fire he formed his canoes from trunks of fallen trees. 

This was the ' ' Stone Age, ' ' and iron and steel were un- 
known and not to be heard of for many thousands of years. 

In various parts of the world copper always has oc- 
curred "native"; i.e., in the metallic form and not in 
combination with other elements as an earth or ore. As the 




THE EARLY HISTORY OF IRON 3 

centuries rolled on, man eventually learned that this soft 
red metal could be pounded into thin-edged implements and 
that it made more useful tools than those of stone, which 
his ancestors had taught him to form. Some of these metal 
implements were hard and had fairly good cutting edges, 
made so by accidental or intentional presence of tin, and 

little did he . ^ 

dream that A 



w 



_-**» — 



Implements of the Stone Age 



the twentieth 

century upon 

finding his 

buried bronze 

implements would think his crude alloy so wonderful and 

talk reverently of a "lost art of tempering copper." 

Gold, too, became known to him because it also occurs 
" native." Its melting point was low enough that he could 
fashion it into ornaments, idols, and other articles for re- 
ligious purposes. But during the hundreds of centuries 
of the "Stone Age" and during much of this — the 
"Bronze Age" — copper, bronze, and gold were the only 
, _ _ metals used. 

*"~ "" ~~ : "T " Though the 

-, _ _____ I! ,g- smiths became 

f . ■_' very dextrous 

in casting and 

Implements of the Bronze Age n ^ • 

modeling 
these metals, they yet knew not iron or steel. 

Round about them during these many centuries, as multi- 
colored earths or rocks, were the ores of various metals. 
They little dreamed that when rightly treated certain of the 
heavy red, yellow, or black earths which lay right at their 
doors could give up that most useful metal, iron. No one 
even had knowledge of such a substance, for, unlike copper 
and gold, iron never occurs ' ' free, ' ' having too great a 



4 NON-TECHNICAL CHATS ON IRON AND STEEL 

tendency to chemically combine with other elements, for ex- 
ample, oxygen of the air, with which, in moist climates, it 
so readily forms "iron rust." Besides, its melting point 
is high and so much heat and carbon are needed for its 
"reduction" from the ore that, during the thousands of 
years that had gone before, it had never been produced. 

But one day by accident and under fortunate coincidence 
of rich ore, high heat, and plenty of carbon in the form of 
charcoal from the wood, a lump of metallic iron was formed 
underneath a pile of logs which had got afire and burned 
fiercely because of a high wind. When pounded between 

two stones this new 
heavy metal, too, was 
malleable and . could 
be formed into a 
spearhead superior 
to anything yet 
known. Every one 
was interested and an 
observant one soon 
"doped out" that 

Primitive Furnace for Smelting Iron , . .-, -■ n 

certain earths could 
be made to yield this new metal, iron. 

The art of extracting it spread slowly, each artisan learn- 
ing from his neighbor, and, as rich ores were plentiful in 
many districts, iron became more and more generally pro- 
duced. Not only in one country was this so but evidence 
shows that in many others — in Egypt, Chaldea, Borneo, 
India, China, etc., — roughly similar processes and crude 
furnaces came to be used. 

Tubal-Cain, supposedly about 4000 years B.C., is men- 
tioned in the Bible as an "artificer in iron and brass," and 
a wedge of wrought iron was buried in the great pyramid 
of Cheops probably as early as 3500 B.C. This wedge was 




THE EARLY HISTORY OF IRON 



recently found and is now the property of the British Mu- 
seum. The Chinese made use of iron many centuries be- 
fore the Christian era, but the Assyrians are supposed to 
have been the first to use the metal on a really extensive 
scale. 

The much discussed pillar at Delhi, India, which is still 
standing in a remarkable state of preservation, is twenty- 
two feet high. It is made up 
of several wrought iron sec- 
tions cleverly welded togeth- 
er. As the natives regard it 
with religious awe, metallur- 
gists have been unable to 
make thorough investigation 
and chemical analysis. While 
the date of its erection is 
somewhat in doubt, it is sup- 
posed to have been about the 
4th or 5th century A.D. 

But from our modern view- 
point those early iron fur- 
naces were queer things. The 
first were little more than 
piles of ore and wood or char- 
coal on the tops of hills where 
a brisk wind would make a 
hot fire. Later, with the invention of the crudest of bellows, 
the smelting was done in small holes in the side of banks 
of clay, charcoal made from the forest trees being used as 
fuel. Indeed, some of these types of furnaces still exist 
and are so operated to-day in neglected districts in Western 
India and elsewhere, producing their little five to 100 pound 
balls of iron after several hours of tedious work. 

When the Eomans invaded Britain (now England), they 




The Pillar at Delhi, India 



6 NON-TECHNICAL CHATS ON IRON AND STEEL 




Milady's Needle 



found the Britons making iron in crude furnaces called 
bloomaries; and not a great deal of improvement, except 
in size, was made up to Queen Elizabeth's time, when 

strict laws had to be 
enacted to prevent 
destruction of the 
forests which were 
being denuded for 
production of char- 
coal, coke, which we 
know so well, not yet having been produced for fuel. 

But the real forerunner of our modern blast furnace was 
the Catalan forge, developed in and named from Catalonia, 
north Spain, where it originated. The Catalan, however, 
and all of such crude early furnaces, including those thus 
far described, produced a variable kind of what 
we now know as "wrought iron," and our mod- 
iron did not appear until about 1350 
when, with larger furnaces, an excess of char- 
coal, with greater heat and other favorable con- 
ditions, the Germans found that the 
pasty, difficultly melting metal 
could be made to ab- 
sorb carbon enough 
to make it easily fus- 
ible. This was the 
secret. 

To state the matter 
in a simple way, iron 
ore, which is essen- 
tially a natural "iron 
rust," is the metal, iron, held in the strong chemical grip 
of the gas, oxygen, which normally forms one-fifth of the 
air we breathe. As you note, the combination forms a sub- 




The Catalan Forge 



THE EARLY HISTORY OF IRON 



stance entirely unlike either the iron or the oxygen, but 
both of these can be regenerated from it (the ore) by chemi- 
cal methods. Under influence of high heat (this is one of 
the chemical methods, by the way), this stranglehold can be 
broken by carbon, of which lampblack, graphite, charcoal, 
and coke, are our most familiar examples. The result, in 
the small, crude, and inefficient furnaces of long ago was a 
disappointingly small ball 
of crude iron, pasty and 
scarcely meltable, even at 
highest heats, but soft and 
malleable when cold. As 
mentioned, it was a variety 
of what is now commonly 
called ' ' wrought iron. ' ' 

The ancients got this far. 

But this was not "cast 
iron. " When, however, 
much more charcoal was 
present in the highly heat- 
ed furnace than was neces- 
sary simply to combine 
with the oxygen of the ore, 
the liberated iron greedily 
absorbed enough of the ex- 
tra carbon to change its 

own nature. . The metal then became very fluid, whereas 
before it had been pasty and stiff even at much higher 
temperatures, or, indeed, at white heat. This liquid iron 
could be "cast," that is, poured into molds and in that way 
made into various useful shapes. It therefore became 
known as "cast iron" because of this property. 

So the brittle metal (cast iron) in our kitchen ranges, 
for instance, is only the early malleable form of the metal 




A Catalan Forge with Italian Trompe, 
or Water Blower 



8 NON-TECHNICAL CHATS ON IRON AND STEEL 

surcharged with or having a large amount of carbon (3y 2 
per cent to 5 per cent) in its make-up, and it is this super- 
carbon content which confers the fluid quality while hot and 
the extreme brittleness when cold. True, there are other 
important constituents in our modern cast iron, but for our 
present purpose they need not be dealt with. 

It has been stated that the ancients got only as far as 
balls of wrought iron. They really got further as their 
very fine sword steels show — the "Wootz" of India, the 
"Damascus" of Syria, and later the "Toledo" of Spain. 
These they produced by heating rich ore in very small, 
closed crucibles with just enough carbon (pieces of wood 
or green leaves) to make what we now call "carbon tool 
steel. ' ' As carbon steel is simply iron which has absorbed 
not over 2 per cent of carbon (cast iron described above 
has a supersaturation with its 3y 2 per cent to 5 per cent 
of carbon and therefore is entirely different) they were 
able to make it in small quantities. When hardened by 
cooling quickly in water, a forged-out blade of this product 
would cleave without dulling its edge a piece of iron, it is 
said, or cut cleanly a tuft of silk floss tossed into the air. 
These steels attained well deserved renown. 

While no one can desire to cast the slightest disparage- 
ment on the product of that period, much of which was 
excellent, astonishingly so considering the period, a mo- 
ment's consideration will convince one that modern prod- 
ucts not only do not suffer in comparison but in reality are 
immensely superior. The ancients had little or no knowl- 
edge of the reason for the proper qualities of their tools 
and they made the metal from variable materials in a 
crude way in such small quantities that little uniformity 
was possible. While some of the product was undoubtedly 
excellent, much must have been less desirable. 

Modern discoveries and inventions, with the great me- 



THE EARLY HISTORY OF IRON 



chanical progress of the last three centuries and the 
scarcely half-century-old application of chemical control, 
have given during recent years products of great uniformity 
and marvelous quality. What can compare with thirty 
thousand pound lots of steel turned out from one Bessemer 
converter each seventeen minutes during the 24 hours in 
the day, that is, a total of 1300 tons or 2,600,000 pounds, 
in which not only the main controlling element, carbon, but 
also four lesser ones, 
silicon, manganese, sul- 
phur, and phosphorus, 
are held within ex- 
tremely narrow limits ; 
or the modern blast fur- 
nace which produces a 
million pounds each 24 
hours, run with the 
same certainty of con- 
trol? Modern high- 
speed steels which are 
every day being made 
have such high quality 
that tools formed from 
them will stand up for 
hours working red-hot 

under a lathe speed of two or three hundred linear feet per 
minute taking a deep cut and ''plowing out" chips faster 
than a laborer can carry them away. 

Modern war armament which has recently been so well 
advertised is sufficient answer as to whether modern metal- 
lurgy is in advance of that of centuries ago. 

The only necessity for such comparisons is that it seems 
to be a failing of many to think that our forefathers were 
more wise and better in other ways than we. It was but 




The German Stuckofen 



10 NON-TECHNICAL CHATS ON IRON AND STEEL 



a few years ago that the fallacious announcement was 
made that during archeological excavations in Egypt there 
had been found a fully equipped telephone system. The in- 
ference intended to be conveyed, of course, was that Bell's 
invention of the telephone had been antedated many hun- 
dreds of years. 

The forerunner of the modern steels was crucible steel, 

first made by Hunts- 
man about the middle 
of the eighteenth cen- 
tury. Previous to his 
time steel had been 
made by the "cemen- 
tation" process by 
which method ham- 
mered-out bars of 
wrought iron 
were given a 
hard steel 
crust by heat- 
ing to a red 
heat in char- 
coal or bone 
dust. Hunts- 
man's product 

began to come so uniform and of such quality that his 
competitors were quite outdistanced. It is related that one 
of them took advantage of a very severe storm to gain 
admittance to the forest forge of Huntsman, who, he knew, 
could not refuse shelter at such a time. What he beheld 
was a very simple thing — the melting in a clay pot of pieces 
of cementation steel. 

Even to-day the crucible process is holding its own where 
quality is the main consideration. It is the method by 




A German Blast Furnace of Fifty Years Ago 



THE EARLY HISTORY OF IRON 11 

which practically all of the tool, automobile, and other 
special steels of to-day are manufactured and can hardly 
be given too high a rating. The newly devised electric 
furnace process is the only possible competitor in sight. 
Of course for quantity and for lower cost the Bessemer 
and the open-hearth processes are the only available ones, 
but crucible steel has been the mighty factor in the com- 
mercial development of the world — at least until the latter 
half of the last century when the two other processes last 
mentioned began to acquire honor of their own without, 
however, detracting much from the importance of crucible 
steel as the steel of "quality." 

Though more interesting than any of the 
"six best sellers" much of the subsequent 
history of iron will have to be passed over 
at this time. We can now only mention 
those very great and revolutionary discov- 
eries and inventions which led to and ab- 
solutely are the basis of the quantity and 
excellence of modern irons and steels ; name- The First Ieon 
ly, the trial for a time of coke made from casting made in 

America 

pit coal by Dud Dudley of England and its 
failure which was turned into a great success a century later 
(about 1713) by Abraham Darby; Watt's invention of the 
steam engine in 1770 which made possible application of a 
strong continuous blast; invention of the process of "pud- 
dling" of iron and of the rolling mill by Cort about 
1784 ; the introduction by Neilson about 1830 of the hot in- 
stead of the cold blast which increased blast furnace pro- 
duction fourfold; the regenerative system of furnace 
heating invented by Frederick and William Siemens; 
and the invention of the Bessemer and Siemens-Martin or 
open-hearth processes which provided methods for steel 
making on such an immense scale that this invalu- 




12 NON-TECHNICAL CHATS ON IRON AND STEEL 

able material was made available for general pur- 
poses. 

It should be repeated that the inventions just mentioned 
have been of the utmost importance to the iron industry, 
and through them only has it acquired its consequence of 
to-day. Without them we would not have the wonderful 
steel bridges, the skyscrapers, the gigantic steel ships, the 
all-steel railway trains, etc., and the hundreds of iron prod- 
ucts that are to-day so plentiful and so constantly about us 
that we disregard their presence. It is difficult thus to 
pass them by, but as most of them will be referred to in 
later chapters we must do so. 

Early iron making in America is of interest to us and 
must be briefly stated. 

The colonists were aware of some of the iron ore de- 
posits about them and sent samples to England where these 
yielded very fine iron. In 1619 a company known as the 
"London Colony" was sent out from England to engage in 
the manufacture of iron at Falling Creek, near Jamestown, 
Virginia, but three years later all were massacred by In- 
dians. It was many years before attempt was again made 
to manufacture iron in Virginia. 

About 1637 the General Court of Massachusetts granted 
to Abraham Shaw one-half of the benefit of "any coles or 
yron stone w ch shall bee found in any comon ground w ch is 
in the countryes disposing." Apparently little resulted 
from this high-sounding grant. 

Real iron-making in America began six years later with 
John Winthrop, Jr., and his "Company of Undertakers 
for the Iron Works" which for many years operated in 
several localities in the New England States. Heaps of 
cinders left from their furnaces may still be seen and testify 
to their very extensive operation. One of Winthrop 's men 
was Joseph Jenks, who became known as the "Tubal-Cain" 



THE EARLY HISTORY OF IRON 13 

of New England. What is claimed to have been the first 
casting made on the Western Continent was made by him. 
It is a small pot, which was acquired and is said to be still 
owned by the family of Thomas Hudson, a descendant of 
Hendryk Hudson. 

Sand molding as used at present was introduced by an 
ingenious Englishman, Jeremy Floris, and is vastly supe- 
rior to the previously used system of molding in clay. Hol- 
lowware began to be extensively produced about this time. 

As the country developed, iron works sprung up here 
and there and various kinds of articles came to be regu- 
larly manufactured. Of the early plants we can only men- 
tion the Stirling Iron Works, at Warwick, New York, which 
made the great 186-ton chain with links weighing 140 
pounds each, which spanned the Hudson River near West 
Point, and where in 1816 was cast the first cannon made in 
America ; the foundry of Sharp & Curtenius, in New York, 
where was cast the first steam cylinder; and the Trenton 
Rolling Mills, which first rolled iron as fireproof structural 
material. 

Before the Revolutionary War the colonies exported con- 
siderable bar and pig iron to Europe, and as early as 1791 
England began to foresee that this country would eventu- 
ally be a serious rival. 

Pittsburg's great advantage as an iron and steel center 
has been due to its proximity to an extensive seam of bitu- 
minous coal and ore in adjacent counties, and to its location 
so near the Great Lakes, which provided cheap water trans- 
portation for the Lake Superior ores. The first iron works 
there was that of Turnbull & Company, which was estab- 
lished in 1790. 

Though Reameur, a Frenchman, is the accredited dis- 
coverer of the process of malleableizing cast iron, Seth Boy- 




14 



THE EARLY HISTORY OF IRON 15 

den, in a little shop in Newark, New Jersey, made malleable 
iron castings a commercial success. 

The utilization of the great beds of high grade coking- 
coal of eastern Pennsylvania, well known as the Connells- 
ville district, and the discovery and development of the 
Lake Superior ore deposits have made the United States 
the leading producer of iron and steel of the world. The 
development of the Birmingham, Alabama, district, also 
has been a chapter of great importance but lack of space 
forbids description at this time. 

"We can have only a very slight appreciation of the debt 
which civilization owes to iron, for practically everything 
we see or with which we daily come in contact contains or 
has resulted from application of iron in some way or other. 
Our cooking utensils and implements (even the enameled 
and tinned ones), the kitchen range, the water and 
drain pipes, and the furnace and heating plants of our 
houses, are they not largely of iron? Our main building 
materials — the steel frames of skyscrapers and bridges, 
and are not even wood, brick, stone, and cement either 
shaped, molded, or of necessity made by aid of iron ma- 
chinery? The conveyances by which we travel — wagons, 
automobiles, street cars, steam railways and steamships — 
how would they be possible without iron or steel? Con- 
sider the power plants of our factories, of gas and electric 
lighting plants, the pumping machinery and distribution 
systems of water works, mines, etc. Would the electric 
current which supplies so much of our power and light be 
known to-day or even be possible but for the magnetic 
properties of iron? And how many of the materials and 
articles which we wear, use, and have about us constantly 
would be in any way possible without the wealth of steel 
machinery and tools which are available and absolutely nec- 
essary for their production? 



16 NON-TECHNICAL CHATS ON IRON AND STEEL 

The iron industry is often spoken of as the barometer 
of a people's civilization. If all iron and iron products 
and their influence upon the world should be obliterated, it 
seems impossible that we could be even started on the road 
to civilization. 

No matter how we try, probably none of us ever realizes 
the immensity and importance of the iron and steel indus- 
try with approximately 460 huge blast furnaces here, 5000 
cast and malleable iron foundries, about 1000 Bessemer and 
open-hearth steel and some 3000 puddling furnaces, and the 
many thousands of factories which each day are turning 
the products of these into rails, plate, wire, pipe, and the 
infinitude of finished articles which enter into and are 
mighty factors of our civilization. Yet with these furnaces, 
forges and factories at our very doors, 99.9 per cent of us 
are entirely oblivious to their wonders and to their pres- 
ence except to be annoyed by their noise and smoke. Even 
the blacksmiths and their service we scarcely note, though 
they are daily fashioning for us a material which is vastly 
more important and more wonderful than any of the 
"Seven Wonders of the World." 



CHAPTER II 
THE RAW MATERIALS 

A story has it that a minister once visited a friend who 
was a zoologist. Upon realizing for the first time how 
highly organized a creature was the humble earth-worm 
with its three-layer skin covering, alimentary canal, 
nephridia or excretory system, reproductory organs, rude 
nervous system, and setae for purposes of locomotion, he 
exclaimed: "Wonderful! I had always supposed that 
worms were only skin and squash." 

With millions of tons of heavy reddish-brown earth from 
northern Michigan and Minnesota going by our doors con- 
tinuously during the shipping season, the position of most 
of us is very similar to that of the minister relative to the 
earth-worm. We know that something is going on but we 
are not aware of its importance or the immensity of it. 

Iron Ore 

Almost every one knows that there are extensive copper 
deposits along the Lake Superior shore of what is now 
northern Michigan. In the 17th century word of these was 
several times taken to Europe where in old publications 
was mentioned a huge ingot of copper from which the In- 
dians chopped pieces with their hatchets. At that early 
date maps of the region were drawn which are wonder- 
fully accurate, and, from time to time over a period of a 
century and a half, adventurers attempted to gain wealth 
in this favored region, 

17 




18 



THE RAW MATERIALS 



19 




However, despite the definite knowledge of considerable 
mineral wealth there and rumored claims of much more, 
Michigan at the time of her admission to the Union in 1836 
bitterly opposed having what is now the northern penin- 
sula included within her territory in lieu of a ten mile wide 
strip of northern Indiana and Ohio, and it has been said 
that she nearly went to war to resist it. Even after the 
discovery of the iron ore deposits, no one realized the full 
importance of the minerals of this region. 

During the many years of campaigning for Federal help 
in the building of a canal at Sault Sainte Marie, the fish- 
eries, valued at $1,- 
000,000 a year, were 
given as the leading 
reason why a canal 
should be built, and 
it was no less a per- 
sonage than Henry 
Clay, who, in oppos- 
ing appropriation for 
this purpose, re- 
ferred to the project and the district as "beyond the re- 
motest settlement, if not in the moon." 

Now, within eighty years of that time, the annual ton- 
nage of shipping passing through the Sault Sainte Marie 
canal is as great as the combined tonnage from the ports 
of. New York, London, Liverpool, Antwerp, and Hamburg, 
and, as against the $1,000,000 value of the fisheries, the 
value at the mines of the ore alone shipped from this region 
amounts to about $100,000,000 yearly. 

As the copper deposits are mostly along the shore of the 
lake and the great iron ore beds occur seven or more miles 
inland, the latter were not discovered until Sept. 19, 1844, 
when William A. Burt, a Deputy United States Surveyor, 



Showing Typical Mesaba Orb Bed Which, 
after Earth Covering is Removed, Be- 
comes an Open Pit Mine 



'siSi 




dL - 


LJSHST ^p^Si r ~, 


— . 








'';•" 


- y^ 


; SsS?- ^ 




P 48 














'll'r-.J 

















Shenango Open Pit Mine, Chisholm, Minn. 




Interior op a Hard or Lump Ore Mine 



20 



THE RAW MATERIALS 



21 



noticed that the needle of a solar compass of which he was 
the inventor became unreliable. In looking about to dis- 
cover the magnetic source which must be the cause of the 
variation, members of his party discovered ore just beneath 
the sod near what is now Negaunee, Michigan. Inventor- 
like, Burt 's only concern was to devise some preventive for 
future interference by stray magnetic currents. He sim- 
ply noted in his book that there was here a deposit of iron 
ore and neither he 



nor any of his party 
profited or appar- 
ently attempted to 
profit from the dis- 
covery. 

The Indians seem 
to have had no pre- 
vious knowledge of 
these ore deposits. 

The first ship- 
ments of ore natu- 
rally were samples 
taken from what 
afterward came to 
be known as the 
Jackson mine and trials of them in blacksmiths' forges 
were made at Jackson, Michigan (from which town went 
the first seriously-minded pioneer, Philo M. Everett), and 
at Cucush Prairie. They were soon afterward tried in a 
blast furnace at Sharon, Pa. 

The first plan was to build forges and manufacture iron 
near the mines. So there was established on Carp River 
a forge to which the ore was hauled in winter when the 
ground was frozen. It turned out, however, that while 
very good bar iron was manufactured here, it could not be 




Showing Ore Body and Shaft Method of 
Mining 



22 NON-TECHNICAL CHATS ON IRON AND STEEL 



delivered in Pittsburg at a cost less than $200 a ton. As 
the market rate for iron then was bnt $80 a ton the plan 
was not financially successful. 

Attention was turned to the shipping of ore to furnaces 
better located as regards coke supply and market. It was 
possible to make this a profitable undertaking only through 

cheap ore handling 
and transportation. 
So, to-day, the ore 
which is better 
adapted than the 
other raw materials 
for handling by la- 
bor-saving devices 
and transporting 
without deterio- 
ration, is taken to the 
coke and limestone, 
and to the market for 
the product. While 
the weight of coke 
used is but half that 
of the ore smelted, 
its greater bulk, loss 
by breakage when 
handled in quanti- 
ties, and deterioration upon exposure preclude its manip- 
ulation in the way which would be necessary to get it to 
the ore. 

The marvelous development of this territory into the 
greatest ore producer of the world, including the hauling 
of the first small shipment on mule back, the building of 
the plank and then the "strap" railroad with grades so 
steep that the small trucks often ran over and killed the 




Lighting the Fuses in a Shaft Mine 




23 



24 NON-TECHNICAL CHATS ON IRON AND STEEL 



mules, the building of the steam railroad, the successive 
building and enlarging of canal locks at Sault Sainte Marie 
connecting for use of ever larger and larger ore boats the 
waters of Lake Superior and Lake Michigan, and the 
growth of ore boat fleets to such size that during the ship- 
ping season scarcely ever is one boat out of sight of an- 
other over the entire 800 mile journey from Duluth to the 
furnaces along Lake Michigan and Lake Erie, is within the 
memory of men still living. Marquette was the shipping 

point during 
the earlier 
days and the 
history of this 
and adjacent 
regions dur- 
ing the latter 
half of last 
century vies 
in pioneering 
flavor with 
the tales of 
our early 
western 
frontiers, and with the more recent Yukon mining camps. 
The first two mines, the Jackson and the Marquette, have 
come to be particularly well known historically. The de- 
velopment of these and other ranges in northern Michigan 
and Minnesota, particularly the Menominee, Gogebic, Ver- 
million, etc., and, since 1890, the Mesaba and Cuyuna, have 
brought about revolutions in ore digging, handling and 
transportation, which followed each other with extreme 
rapidity. The ore carrying boats, for instance, may al- 
most be said to have jumped from a length of three hun- 
dred to six hundred feet, and the Sault Sainte Marie canal 




The Routes by Which Lake Superior Ores Go to the 
Furnaces 




25 



26 NON-TECHNICAL CHATS ON IRON AND STEEL 



locks were several times almost immediately outgrown, 
though rebuilt again and again, each time so much larger 
than before that they were deemed impossible to be out- 
grown. 

Practically all of the ore beds, with the exception of the 
Mesaba, yield hard or lump ores and most of them are shaft 
mines in which mining has to be done underground and the 
ore blasted down. Blast furnaces had never used any but 
lump ores when along came discovery of the immense soft 

ore deposits lying- 
just beneath the sur- 
face of the ground 
over a region one- 
hundred miles long 
in what is known as 
the Mesaba district 
of Minnesota. 
These soft ores 
were so accessible 
and so rich that they 
drew the attention 
of the iron makers 
of the whole coun- 
try. But, alas! While perfectly good in every other re- 
spect, they were merely dry powder and not adapted to 
blast furnace methods. There were great discussion, ex- 
citement, and ridicule among or at those who invested 
in these soft ore mines. Eventually, of course, blast fur- 
nace men worked out feasible methods of converting 
soft or what are termed "Mesaba Range" ores into 
iron in the blast furnace. Those brave spirits, who in 
the face of ridicule dared to invest in and develop 
Mesaba properties, have long been reaping their finan- 
cial reward which still shows no sign of diminishing, 




Showing Other Typical Ore Bodies, Shaft 
Mined 




27 



28 NON-TECHNICAL CHATS ON IRON AND STEEL 



as "Mesaba Range" mines are "the" mines of to- 
day. 

"While it may be done, it has not been found desirable 
to make up the entire "burden" or furnace charge of soft 
ores alone as long as lump or hard ores are obtainable to 
mix with them, but often more than half is soft ore. 

While ores from the shaft mines, called "Old Range" 
ores, are won by going down into the earth sometimes as 
far as 3,000 feet, drilling holes in the rock, blasting down 
the ore, and loading it into buggies which are hoisted to 

the surface, 
''Mesaba 
Range" ores 
are made 
available by 
simply ' ' strip- 
ping" off the 
thin earth 
covering, then 
caving or 
loading with 
steam shovels 
the soft ore 
into railway cars. Some of the illustrations presented 
show the ore trains and shovels, and the manner in which 
the open pits are worked in terraces. 

One naturally wonders how it is possible to mine and 
carry these ores to the shipping ports of Duluth, Superior, 
Two Harbors, Marquette, Ashland, Escanaba, etc., put 
them aboard ore carrying boats, transport them by steam 
power to Milwaukee, Chicago, Gary, Detroit, Cleveland, 
Pittsburg, Buffalo, and the many other iron centers and 
convert them into iron and steel at a profit. This, of course, 
is only possible because of the inventive genius of man. 




Starting an Open Pit Mine. The Earth Cover- 
ing is Being Removed 




29 



30 NON-TECHNICAL CHATS ON IRON AND STEEL 



For every operation ingenious machinery has been con- 
structed which has brought the cost of such operations to 
its lowest terms. 

By modern methods the cars carrying the ore from the 
mines are run up trestle-work into positions above the ore 
bins high over the docks. The mammoth ore carrying 
boats are merely steel shells with quarters for crew and 
machinery at bow and stern, and hatches built with exact 
twelve foot centers between. They are tied alongside the 
dock, long steel chutes, also spaced twelve feet apart, are 

lowered along 
most of the 
length of the 
boat and the 
ore slides into 
the vessel's 
hold evenly 
all along as it 
has to do, else 
the buoyancy 
of lighter 
parts of the 
boat might 

break the frail shell. The entire load of 10,000 tons of ore 
is ordinarily taken aboard in less than one hour. Pulling 
out immediately the vessel traverses Lake Superior, the 
Sault Sainte Marie canal, Lake Michigan or Lakes Huron 
and Erie as the case may be, and ties up at the dock at 
destination. Years ago it would have been unloaded by 
men with buckets or wheel-barrows, requiring some days 
at best. Now, however, the hatches are uncovered and sev- 
eral ore unloaders with huge clam shell buckets taking as 
high as fifteen tons of ore at a "bite" descend like vultures 
upon it. Within four or five hours the boat is again empty 




Ore Cars are Unloaded by Gravity at Docks. The 

Chutes Then Convey the Ore from the Ore 

Pockets into the Boat's Hold 



THE RAW MATERIALS 



31 




Hoover & Mason Unloaders at the Illinois Steel Co., 
South Chicago, III. 



with no manual labor having been done upon the ore from 
the mine to the furnace pile with the exception of a little 
heaping up of the ore in the corners of the boat's hold, 
which the ore unloaders could not reach. 

A young 
man named 
Alexander E. 
Brown could 
not bear, in 
the old clays, 
to see the ore 
so awkwardly 
unloaded, and 
in 1880 start- 
ed the procession of ore unloading devices. There are 
now several successful ore unloaders of which the Brown 
hoist, the Hoover & Mason, and the Hulett are prob- 
ably the best known. With the Hulett unloader the 
operator has to be an aviator, as his position is directly 

above the 

. ! grab bucket. 

a . "> ..._> ■;.-. i He descends 

into the hold 
with the buck- 
et, comes up 
with it and is 
with it in its 
entire journey 
from the 
boat's hold to 
the dump and back again. It must be dizzy business. 

Time is too precious to hold the boat at the dock long 
enough that each bucketful, large as it is, can go directly 
to its final bin. It is dropped just back of the unloading 




The Hulett Unloader. Note the Operator's Head in 
White Spot Just Above the Grab 



32 NON-TECHNICAL CHATS ON IRON AND STEEL 



machine from which it is again picked up by other buckets 
which carry it back toward the furnaces and deposit it in 
cement ore troughs awaiting further journey to the ore 
house, from which it goes to the furnaces. The empty 
ore boat immediately coals with whole car loads of the 
fuel dumped into chutes leading to her bunkers by the car 
dumper and proceeds on her way back to the mines for 
another cargo of ore. The round trip, including loading 
and unloading, requires but seven days. 

As in many 
, ,.*.*•(% other lines of 

c o m m e r - 
cial endeavor 
of to-day, 
speed and 
large tonnage 
have been the 
aim and it 
would seem 
that in ore 
handling and 
conveying de- 
vices the limit 
has about been reached. The big steam shovels, gravity 
docks, ore tanks or boats, and unloading and coaling de- 
vices, with the low cost of water transportation have made 
our modern iron and steel preeminence possible. To show 
the importance to us of this water transportation, we might 
mention that the rate for carrying ore from Lake Superior 
ore ports to the Lake Erie furnaces has been as low as 
$.0007 per ton per mile while the transportation cost by 
way of a well operated railway at that particular time was 
more than $.005 per ton per mile — more than seven times 
as much. 




A Good View of the Hatch System op Modern Ore Boats 
and Four Hulett Unloaders at Work 



THE RAW MATERIALS 



33 



Though for some years past more than three-quarters 
of all of the iron ore used in the United States has come 
from seven or eight mines in the northern peninsula of 
Michigan and the adjacent part of Minnesota, it must not 
be understood that the Lake Superior mines are the only 
ore deposits in this country. Figures show that such an 
inference is far from the truth. It is true, however, that 




The Rehandling Bridge with Stock Ore Pile and Blast Furnace at Rear 



they have made the United States what it is, the leading 
iron producer of the world. There are still immense quan- 
tities to be mined on the Lake Superior ranges. Their 
heavy production of cheaply handled high grade ore has, 
of course, held back development of other districts, which 
also have great natural resources. The Birmingham, Ala., 
region for instance, is a great ore and iron producer, right 
now producing the third largest tonnage of any district in 



34 NON-TECHNICAL CHATS ON IRON AND STEEL 



the country. Some time in the not far off future, Alabama 
with her great deposits of iron ore, coal, and other natu- 
ral resources is going to announce herself in no small voice. 
New York, Pennsylvania, Tennessee, and Virginia rank 
next after Minnesota, Michigan, and Alabama as ore pro- 
ducers, and several other states of the Union are not pau- 
pers in resources of iron ore. 

We should not get so enthusiastic over our ore supply and 
iron production as to think that other countries are devoid 
of such material. Almost every civilized country has ore 

enough that it 
does pretty 
well. With 
many the 
trouble is that 
the ore has 
objection- 
able constitu- 
ents or that 
supply of 
cheap fuel is 

Holett Grab Buckets in the FIold of an Ore Boat not available. 

Germany has 
large deposits of iron ore, but until the invention of the 
basic Bessemer process about 1870 she was handicapped 
because of the high phosphorus content of her ore. The 
basic processes, both Bessemer and open-hearth, allow of 
the removal of this phosphorus during the conversion into 
steel, and they therefore brought Germany to the front as 
an iron producer. 

The excellence of Sweden's iron and steel has long been 
known the world over. Sweden produces approximately 
one per cent of the world's total production of iron and 
steel, but her ore has been of such high grade that iron made 




THE RAW MATERIALS 35 

from it has maintained its position as a standard for use in 
the manufacture of highest grade crucible steels. The very 
finest steels for cutlery and tools, and even the softer grades 
of steel of northwestern Europe, have been made from 
Swedish iron as a base. 

Iron ore, of course, is classified by geologists and chem- 
ists into varieties with such names as hematite, magnetite, 
siderite, etc., which here little concern us. 

To be worked at a profit, the iron content of the ore must 
be high with the smallest possible amounts of undesirable 
impurities, particularly phosphorus, sulphur, and silica. 
There are, however, certain impurities which are not un- 
desirable, for instance, lime, which will act as a flux and 
neutralize the effect of some of the undesirable impurities. 
For these reasons the prices for iron ore are based on the 
iron content and modified by the relative amounts of unde- 
sirable and desirable impurities. Phosphorus is almost a 
domineering factor and at present approximately fifty cents 
a ton more is paid for Bessemer ore (that containing less 
than .050 per cent phosphorus) than for non-Bessemer ore. 
As might be expected the best ores have been the first used 
and the grade is constantly falling. Instead of the 66 per 
cent iron ores of some years ago those coming nowadays 
contain not much more than 59 per cent of iron and the 
Bessemer ores described above are getting scarcer, so that 
for some years practically all of the furnaces have been 
mixing with them as much higher phosphorus ore as could 
be used without pushing the phosphorus content of the 
mixture over the allowable limit. 

We often hear people surmising what is to become of us 
when all of the iron ore of this planet has been used. There 
is no harm in taking stock of resources and in this case it 
does us much good. It happens that each time the count is 
taken of iron ore available and that which under future and 



36 NON-TECHNICAL CHATS ON IRON AND STEEL 

better methods of working can be utilized, we find our- 
selves immensely better off than the previous report had 
made out and we have less cause to worry about the future. 
The last inventory was taken by the extremely ambitious 
International Geological Congress held at Stockholm, Swe- 
den, in 1910. It shows that the world yet has enough rich 
ore to make 10,192,000,000 tons of iron, and, a further sup- 
ply of ore for 53,136,000,000 tons of iron, which could be 
used if necessary. 

So we will get along for a while yet. 



CHAPTER III 

THE OTHER RAW MATERIALS 

Since the beginnings of iron manufacture, charcoal has 
been a favorite fuel. Though during the past two cen- 
turies coke has grown to be the standard, with anthra- 
cite and some few bituminous coals finding use in certain 
favored localities, charcoal may be considered the fuel 
which developed the 
iron industry, at least 
until recent years. 

Charcoal 

As most of us 
know, charcoal is 
completely charred 
wood, usually hard 
wood, though some- 
times resinous or other soft woods are used. Of well-dried 
timber more than 50 per cent by weight is moisture. This 
and certain other constituents are driven off by heat in the 
absence of air, which process is usually called "destructive 
distillation. ' ' 

By primitive methods a considerable part of the wood 
was completely burned and wasted during the production 
of charcoal. Stacked in piles or long rows the cut wood 
was well covered with earth, except for a small opening 
at the top through which the fire was lighted down a center 

37 




Old Charcoal Kilns, near Negaunee, Mich. 



38 NON-TECHNICAL CHATS ON IRON AND STEEL 



cavity left to the bottom of the pile. The air coming in 
through the opening at the top was sufficient to keep the 
wood smoldering. After a period, which had been shown 
by experience to give the best results, the opening was 
closed and the fire smothered. 

Brick ovens of the beehive shape were built at a later 
date where considerable charcoal was to be made. These 
were operated on much the same general principle as the 
meillers or earth-covered piles, described above. The fire 
was lighted at the bottom of the central cavity of the corded 
wood, the only air at first coming from the top, though 

later in the process 

| a little was admitted 

I ,j through holes in the 

> „ ^ >■ I walls. After about 

ten days, when gas 

ceased to come off, 

the kiln was tightly 

closed for a period of 

twenty days more for 

the fire to die out and 

the charcoal to cool. 

By both of these processes valuable constituents were 

burned or driven off by the heat and lost. These were 

mainly methyl alcohol, acetic acid, and wood tar. 

Modern industry so emphatically disapproves of any 
waste of materials that apparatus has been devised to pro- 
duce charcoal which allows of recovery of the by-products 
at the same time. In northern Michigan, which is practi- 
cally the only district in the United States in which the 
charcoal industry as an industry still survives, long steel 
tubes or retorts are built with brick fire-boxes under each 
end, much as a stationary boiler is set. Into these retorts 
are run steel cars loaded with the wood. The retorts being 




'i 



Beehive Coke Ovens 




txij i.i- H.u.4-|i 



39 



40 NON-TECHNICAL CHATS ON IRON AND STEEL 



closed, the heat drives or distills off the moisture and gase- 
ous compounds through pipes connecting them with con- 
densing apparatus. After about twenty hours the wood has 
been charred, the doors of the kilns are suddenly opened 
and the cars are rushed into other and similar retorts for 
cooling, while fresh loads of wood replace them in the first. 
As may be surmised vast quantities of wood and of 
wood-producing land are required for extensive charcoal 
manufacture, and this is the most serious problem for the 
manufacturer of charcoal. Several square miles of timber 
land must be cut over each year and the wood efficiently 

transported in order 
to operate a large 
plant profitably. 

Pig iron as a by- 
product is a rather 
novel idea, but that is 
practically what the 
charcoal pig iron 
produced in our Lake 
Superior region is. 
Several companies 
operate wood distillation plants for the production of 
methyl alcohol, acetic acicl, acetate of lime, etc., and use 
their charcoal in the manufacture of charcoal pig iron from 
the ores so close at hand. 

The very low sulphur content and the small amount of 
ash have been the great advantages possessed by charcoal 
over other solid fuels. Eesulting characteristics made char- 
coal pig iron a former favorite for manufacture of certain 
articles such as chilled car wheels, etc., and it, therefore, 
brought a higher price than coke pig iron. During recent 
years, however, by careful selection of coal and improve- 
ments in the coking process the sulphur and ash of coke 




Beehive Ovens 



THE OTHER RAW MATERIALS 



41 



have been so reduced that charcoal has not so great an ad- 
vantage as formerly. Charcoal iron to-day brings only 
about $1.50 per ton more than coke iron ; whereas, the dif- 
ferential a few years ago was as great as $5.00 or $6.00 
per ton. 

Charcoal is quite fragile and structurally weak, so much 
so that blast furnaces for its use cannot be built higher 
than sixty feet ; whereas, the great strength of coke allows 
them to be built to exceed one hundred feet in height with 
correspondingly in- 
creased output. What 
this means may be 
realized by every one 
conversant with the 
demands of modern 
industry. 

Coke 

As charcoal is com- 
pletely charred wood) 
so coke for analogy's 
sake may be said to 
be completely 

charred coal, practically always of the bituminous type. By 
" baking" bituminous coal at a cherry-red heat, its volatile 
constituents are driven off as the well-known "coal-gas" 
of almost every small town, and a strong, brittle and por- 
ous material or coke residue is left. If the baking is done 
without any admission of air to the retort, practically none 
of the coal burns and the "cake" or coke which is left con- 
tains the ash of the original coal and what is known as the 
"fixed carbon," i.e., carbon which cannot be distilled or 
driven off by heat alone, though it would burn were air 
admitted. 




Charging Coal into the Ovens 



42 NON-TECHNICAL CHATS ON IRON AND STEEL 



The gases or volatile constituents which are given off 
consist mainly of moisture and a mixture of gaseous chemi- 
cal compounds, which are known as "hydro-carbons." 
These contain that part of the carbon of the original coal 
which does not remain as "fixed carbon" in the coke. 

Just why some coals will coke while others of apparently 
the same composition as shown by the chemist's analyses, 
will not, but instead of the hard brittle mass will leave a 
heap of brown or black powder, is not as yet definitely 

. known. It is easy 
enough for chemists 
to determine with ac- 
curacy the amounts 
of hydrogen, nitro- 
gen, oxygen, carbon, 
sulphur, and other 
elements; but it is a 
difficult and perhaps 
an impossible matter 
to determine just how 
these elements are 
"hitched up" in the 
very complex mineral, 
coal, — one of the most complex substances which we know. 
Various theories have been advanced in the attempt to 
explain the coking quality. A bulletin of the United States 
Geological Survey claims that the relative percentages of 
hydrogen and oxygen in the coal determines it ; others have 
held that it depends upon the compounds of a tarry or as- 
phaltic nature present. The fact remains that some coals 
coke without trouble, while others do not coke at all. As 
yet the only real way to tell whether a new variety' of coal 
will or will not coke is to try it. 

Since 1713, when Abraham Darby in England succeeded 




Quenching after Coal Has Been Coked 



THE OTHER RAW MATERIALS 



43 



in introducing it as a substitute for the fast disappearing 
charcoal for use in blast furnaces, coke has become the 
standard fuel. It is very strong and will bear up under 
the great weight of iron ore and limestone with which the 
furnace is charged. So furnaces for use with coke may be 
built much larger than those in which charcoal is to be 
the fuel. The porous nature of coke allows it to burn rap- 
idly with intense heat, so that the output of an iron works 
is greatly increased through its use — a very desirable thing 
in these days of big 
things. It has its dis- 
advantages, of 
course, mainly high 
sulphur, a deleterious 
substance for which 
molten iron, unfortu- 
nately, has a vora- 
cious appetite, and a 
rather high percen- 
tage of ash which 
must be fluxed out. 
But all in all, it is 
a very desirable fuel 

for blast furnace and other metallurgical purposes, as is 
shown by the fact that it is used in the production of about 
ninety-nine per cent of all iron and steel now made. 

What is known as the Appalachian coal region produces 
coal for more than seventy-five per cent of the coke made 
in the United States. This region includes the strip of 
territory extending from Western Pennsylvania and Ohio 
down to Tennessee, Georgia, and Alabama. The famous 
Connellsville district is a part of this region. 

Illinois and Indiana have a great deal of coal, which, 
however, has rather indifferent coking qualities. Almost 




Drawing the Coke 



44 NON-TECHNICAL CHATS ON IRON AND STEEL 



constant experimentation has been carried on in the attempt 
to induce these semi-coking coals to coke. The best that 
has so far developed is the use of a considerable percentage 

of them in admixture 
with coals of good 
coking qualities. 
Such mixtures yield 
quite satisfactory 
coke. 




Large Pieces op Coke 



The Beehive Oven 
Process 

In the old days 
there was no desire 
or incentive to avoid 
waste of coal re- 
sources. If during 
the coking process some air got into the oven and part of 
the coal was burned, or if all of the gas given off was 
wasted, it did not matter. There was plenty more of coal 

and the thing desired 
was to get the requi- 
site coke in the quick- 
est and cheapest way. 
In Western Penn- 
sylvania, Ohio, and 
Virginia, were great 
beds of high grade 
coking coal. In this 
region a n d particu- 
larly around Pitts- 
burg, numerous blast furnaces and steel mills grew up. 
The coke for these was made in the most convenient way — 
in the wasteful beehive ovens. 




Where Coals Are Pulverized and Mixed for 
Coking 



THE OTHER RAW MATERIALS 



45 



As the name signifies, these ovens or retorts are brick 
chambers shaped like beehives. In the larger plants they 
are built either in single rows against long hills or in dou- 
ble rows back to back. Over the tops of the ovens in each 
row runs a car called a charging "lorry." Coal is poured 
from the bottom of this through a hole in the top of each 
oven while it is still hot from the preceding charge. No air 
gets in except that admitted through the hole in the oven 
top and a small slit left over the one side door, through 
which the coke is drawn when the coking process is finished. 
The heat of the oven starts the distillation of the moisture 
and the volatile com- 
pounds which escape 
through the hole in 
the oven top. The 
small amount of air 
admitted burns a lit- 
tle of the coal and 
gas and raises the 

fprnnpratnrp of flip Battery of By-Pkoduct Coke Ovens, Showing 
ILIIipeidlUie Ol L 11 e Gas-collecting Main 

oven to that required 
for coking. 

After 48 or 72 hours a spray of water is thrown in over 
the glowing coal to quench the fire. The partially cooled 
coke is drawn through the open door, sorted and loaded into 
cars for shipment. 

Though this method of coking is a very wasteful one, it 
yet produces the larger quantity of the coke made in the 
United States. However, conditions are rapidly changing 
and it will not be many years before the much less wasteful 
"by-product" process gains the ascendency. By 1914 it 
had already come to produce about twenty-five per cent of 
the total coke made here, and -since that date the percentage 
has been rapidly increasing. 




46 NON-TECHNICAL CHATS ON IRON AND STEEL 




Top op Ovens with Charging Bin and Lorry at 
Far End 



The By-product Process 

By this system of coking a greater yield of coke is ob- 
tained and most of the by-products are saved. The value 

of the latter depends 
largely, of course, 
upon local conditions, 
such as transporta- 
tion, costs of the ma- 
terial, cost of labor, 
and available market 
for the coke oven gas. 
They are usually fig- 
ured as having a 
value of $1:50 per ton of coal coked, equivalent to a total 
of $71,000,000 per year for the coal coked in the United 
States. 

The ovens and apparatus required are considerably more 
expensive, but, since 
this industry has de- 
veloped in this coun- 
try during the last 
twenty-two years to 
a point where one- 
quarter of all of the 
coke manufactured is 
made by the by-prod- 
uct process, there can 
be no doubt that it is 

a profitable proposition and that eventually the wasteful 
beehive ovens will be a thing of the past. 

Practically all of the types of by-product coke ovens in 
use have been developed in Germany or Belgium, where 
circumstances forced earlier conservation of resources than 




Lorry for Charging Coal into Ovens 



THE OTHER RAW MATERIALS 47 

in this country. The three best known types are the Semet- 
Solvay, the Otto Hoffman, and the Koppers — the latter a 
recent arrival. They differ mainly in details of construc- 
tion and operation. 

In a general way a "battery" of coke ovens consists of 
from 40 to 80 long narrow brick-walled chambers placed 
closely side by side with heating flues or "checker work" 
between them. The fire for the baking process is in these 
flues, which are interconnected, and the heat developed is 
sufficient to drive off the moisture and volatile substances 
of the coal in the narrow chambers just on the other side 
of the brick walls. 
Charging is done by 
a "lorry" as in the 
beehive process. 
After from seventeen 
to twenty-four hours 
at a red heat, the 
coke is "pushed" 
from the ovens, one machine for pushing coke from ovens 
after another, by an 

electric ram which enters at one end. The 30 x 7 x V/ 2 foot 
block of glowing coke emerges from the other end, where, 
breaking under its own weight into good-sized pieces, it 
falls into a steel car on a track just beneath. A spray of 
water quenches it and it is taken to the storage bins to 
be sorted. 

Rich coal-gas is the main by-product. That which comes 
off during the first seven hours is the richest and has the 
greatest illuminating or "candle" power. After washing 
free from dust, tar, ammonia, etc., the gas is usually run 
into holders or tanks from which it is distributed for use 
for illuminating or for heating purposes. That which comes 
off during the latter part of the coking period has much less 




48 NON-TECHNICAL CHATS ON IRON AND STEEL 



of those constituents which give illuminating value. It has 
good heat value, however, and as fuel is required for keep- 
ing the ovens up to the coking temperature, this poorer gas 
from the coking chambers is switched into and burns in the 
flues between the coking chambers as mentioned. 

Thus the larger part of the gas is sold to customers, usu- 
ally in the city near which the ovens have been located, 
and the poorer part is utilized in heating the ovens and the 
steam boilers which run the plant. 

The coal tar, which 
the German chemists 
have made so famous 
through its manufac- 
ture into the almost 
endless variety of 
beautiful dyes, is an- 
other of the by-prod- 
ucts which is recov- 
ered by this, but 
burned or lost in the 
beehive oven process. 
From a long main 
over the tops of the 
ovens which connects the gas pipes, the tar flows along 
with the gas to the scrubbing and gas cleaning plant, where 
by rather intricate operations it is freed from other sub- 
stances. 

In this country much of the tar is used for building pur- 
poses, etc., and some as fuel, but not much has been made 
into the chemical products for which Germany is so 
famous. For a long time a few dyes and other chemical 
compounds have been made here from coal tar. Since the 
early days of the war in Europe and the cessation of 
imports of such materials on this account, there has come 




Quenching Car Awaiting Its Load 



THE OTHER RAW MATERIALS 



49 



about considerable expansion in their manufacture here; 
but it is doubtful if the time is yet ripe for a wholesale 
entry into the manufacture of these coal tar "deriva- 
tives," especially the very extensive variety of dyestuffs. 

Naphthalene and benzol from which many other chemical 
compounds as well as munitions of war can be made, are 
among the by-products. 

Most of the ammonia which the corner drug store sells, 
comes from the by- 
product manufacture 
of coke. The largest 
part of the ammonia 
which is produced in 
the process, however, 
is manufactured into 
sulphate of ammonia, 
a well-known fertil- 
izer. 

Coal 

Anthracite or hard 
coal has been used 
in certain districts 
in the United States, 
especially in New 
Jersey and eastern 
Pennsylvania. It is 
not an ideal fuel as it 
is too solid to burn rapidly, spalls or cracks under heat and 
interferes with the blast. Since 1860 when coke became 
available here much less coal has been used, though some 
is yet used in admixture with coke. Some bituminous coals 
which contained little tarry matter also have been used in 
this way. 




Quenching the Coke 



50 NON-TECHNICAL CHATS ON IRON AND STEEL 




Coke Going from Quenching Car to Bins 



Fluxes 
Limestone, the rock which is ordinarily used for fluxing 
purposes, needs no introduction to any of us. As the 

marble of statuary, 
the material of which 
oyster and other sea 
shells and the white 
tombstones of our 
cemeteries are com- 
posed, it is well 
known. Any of these 
varieties of the ma- 
terial may be used 
for fluxing purposes, 
but usually it is lime- 
stone which is quar- 
ried for the purpose 
or obtained as chip- 
pings or spalls from 
building blocks. 

The active agent, 
which produces the 
chemical or fluxing 
action in t h e blast 
furnaces, is carbon- 
ate of calcium (lime) 
of which limestone 
contains about 98 per 
cent. Dolomite is a 

Loading Coke in Box Car mixture of Carbon- 

ates of lime and mag- 
nesium, about 53 per cent of the former and 45 per cent 
of the latter, and is sometimes used in place of limestone. 




THE OTHER RAW MATERIALS 51 

Fluor spar, a rock composed of calcium and fluorine, is 
used in small quantities in some of the metallurgical proc- 
esses. It is a very powerful flux. 



CHAPTER IV 
THE BLAST FURNACE 

Up the dark tower shoots the elevator with its "buggy" 
of coke. Its speed is not conditioned to the comfort of man, 
who is not supposed to be a passenger, except the occasional 
laborer whose duty as buggy-pusher requires his presence 
on twelve-hour shifts at the top. So we, whose exploratory 
proclivities have led us at the office to sign away our lives 
for grant of a pass to the blast furnace, find our breath 
about taken from us with the first mad dash into the dark- 
ness of the climb. That stone tower had looked much more 
innocent from below. 

But now the rickety elevator has as suddenly emerged 
into the light again and stopped abruptly at the charging 
floor which extends across the chasm to the top of the 
furnace. 

As the smoke-begrimed buggy-pushers rush the buggy 
of coke across to the furnace bell, we have opportunity to 
notice that we are a full hundred feet above ground. Just 
here, seemingly so close that we can put our hands on them, 
in a row, are the round steel tops of the four stoves which 
are for the purpose of preheating the blast. The huge 
pipes, dust arresters, tanks, and buildings, all so necessary 
to the plant, look almost like a tangled mass from our high 
station, while the charging floor upon which we stand, the 
shoulder-high steel fence around it, the furnace top, the 
adjacent stoves and in fact everything for a half mile 

52 



THE BLAST FURNACE 



53 



around us, is colored yellow-red with iron dust. We un- 
derstand the reason for this when the buggies of ore which 
have succeeded the coke are dumped into the funnel-shaped 
depression around the conical bell at the center. As the 
huge bell is lowered and the charge slides in there is con- 
siderable blowing out of the fine ore dust, which, in fact, 
continually "oozes" out of all crevices under the heavy 
pressure of the blast inside. 

Day and night, month in and month out, during the life 
of the fire-brick lin- 
ing of the furnace, 
this routine of charg- 
ing, first coke, next 
the theoretically cor- 
rect charge of an- 
alyzed iron ores, then 
limestone, in rotation 
goes on. From 6 a.m. 
to 6 p.m. and from 
6 p.m. to 6 a.m. on 
twelve-hour shifts, 
alternating gangs of 
laborers push the 
buggies across to the furnace top, dump and return them 
to the elevator already up with another load. 

The incessant quiver of the iron plates beneath our feet 
with the rumbling and groaning from the inside of this 
monster are disquieting and the thought constantly recurs : 
"What if this powerful creature should just now rebel, as 
quite occasionally occurred in the old days when all of its 
moods had not been so well understood?" For this king 
of metallurgical devices, though gentle and obedient as a 
lamb under proper treatment, is a domineering fury when 
it has dyspepsia as occurs whenever its attendants are re- 




Hand-fed Blast Furnace 




54 



THE BLAST FURNACE 



55 



miss in their attentions to its diet. "Those explosion doors 
just below the furnace top — are they in working order and 
would they be adequate?" But whether, as in recorded 
instances, the whole furnace top is torn off as evidence of 
its wrath, or its displeasure is exhibited in a milder way, 
we much prefer to be absent. The thought is disquieting 
and We are glad to 
leave. 

Unwilling to test 
again the elevator for 
the downward trip, 
we take to the nar- 
row iron stairway 
which leads from the 
top of the furnace to 
the ground. But this 
is worse than the ele- 
vator, for the stair 
treads are very nar- 
row and made only of 
three slender iron 
rods. To our palpi- 
tating hearts they 
seem to give very in- 
secure foothold and 
the gaps show that 
there is nothing but earth beneath us, and that a hun- 
dred feet below. To make matters worse, before we 
creepingly get half way down some visitors below have 
stopped to watch our slow and trembling steps and 
our nervous clutch on the low "stingy" hand rail. We 
hear them innocently inquire of one another why we 
move so slowly. We wish that we could appear brave, 
especially before the women in the party, but we could 




'Fireworks" at the Cinder-Notch 



56 NON-TECHNICAL CHATS ON IRON AND STEEL 



not move with greater alacrity if our lives depended 
upon it. 

Once below again with our breath regained, things are 
more interesting. The red-hot molten slag which has just 
been tapped out is running from the furnace along a long 
trough into a ladle six feet high resting upon a car on the 
railway track alongside the "cast house," as the huge 
structure which houses the lower part of the furnace is 
called. This smoking, molten slag stream gives off a pow- 
erful sulphur smell 
and throws a lurid 
glare over everything 
round about. 

The furnace super- 
intendent is just ex- 
plaining to the other 
party that No. 2 fur- 
nace has been "hang- 
ing" for a couple of 
days and is still dan- 
gerous. "If you real- 
ize," said he, "the 
great weight of coke, 
ore, and limestone in that furnace, you can see what a 
splash it would make if the clogged, bridged part with all 
above it should fall suddenly into the molten pool in the 
'hearth' of the furnace. Two years ago No. 1 broke out 
and the molten metal caught and burned to death one of 
our men and injured several others. 'Hanging' does not 
occur when the furnace is working right, but failure of the 
charge to come down evenly is very serious sometimes. 
A blast furnace is like a coquette; she has to be handled 
just so, and even then you cannot always be sure what she 
is going to do next. 




The Slag Dump 



THE BLAST FURNACE 



57 



CHARGING FLOOR 



"Oh -yes, — where does the iron come from? Well, we 
often read nowadays of a man and his 'affinity.' Now the 
chemist has used that word 'affinity' for years to describe 
the liking or attraction of one chemical 'element' for an- 
other; in fact, that is where this recent colloquial use of 
the word originated. 
Iron ore is nothing 
more nor less than 
metallic iron, the ele- 
ment, chemically 
combined with oxy- 
gen, another element 
w h i c h constitutes 
one-fifth of the air we 
breath. Under condi- 
tions produced in the 
blast furnace, though 
for centuries wedded 
to iron, oxygen de- 
serts him for her ' af- 
finity' carbon, which 
is best known to you 
as coke, coal, or char- 
coal. The iron, now 
free, becomes molten 
at the high tempera- 
ture encountered 

(about 2800° to 3000° F.) and descends into the 'hearth' or 
bottom of the furnace, while oxygen and her new partner 
escape out of the top of the furnace in gaseous form. When 
molten iron has accumulated in the hearth to the extent de- 
sired it is tapped out as you will soon see. 

"The limestone charged has 'affinity' for dirt and cer- 
tain other impurities of the ore which it removes in molten 




SION LEVEL 



BUSTLE PIPE 



COM BUSTION (or coke) 
TUYERE "-EVEL 

MOLTEN SLAG 
MOLTEN IRON 



TAP HOLE 



Diagrammatic Sketch of Blast Furnace 



58 NON-TECHNICAL CHATS ON IRON AND STEEL 



form as the 'cinder' or 'slag' which is there running into 
the ladle. When cold, this cinder is a dark greenish-black, 
glassy substance, which of recent years has come to be used 
to a certain extent in the manufacture of Portland cement 
but is mainly used for filling-in purposes. Some is crushed 
and utilized in concrete mixtures and for road building. In 

Chicago considerable 
land has been 'made' 
by dumping slag into 
the lake, and South 
Chicago is reported 
as standing on a 
swamp which has 
been filled in with 
slag from the steel 
works there. 




innfinnnnnfinfinnn rPPinnfinnnnniifm^ ^ 




iP 



iHnnnnnnnnnnniu Lnnnjionfuififiniui] 



MAIN RUNNER 



Old-Fashioned Pig Bed 



"This immense 
furnace is simply a 
strong steel shell 
lined two or three 
feet thick with fire 
bricks. At the 'bosh,' 
which is the region 
where the greatest 
heat is produced, hol- 
low bronze plates are 
inserted among the bricks of the lining through which cir- 
culating cold water keeps the bricks from being fused. 

"The hot gases which are led from the upper part of the 
furnace through that brick-lined 'downcomer' are burning 
in three of those ' stoves ' to heat them, while cold, clean air 
from the blowing engines is coming through the other stove, 
which, ten minutes ago, when it was put on blast, was the 
hottest of the four. It is now giving up part of its accumu- 



THE BLAST FURNACE 



59 



lated heat to the blast on its way to the furnace. Switching 
the cold incoming air every little while from a partially 
cooled stove through 
a hotter one while al- 
lowing the former to 
reheat, provides con- 
tinuous blast of a 
temperature of 800° 
to 1400° F. The 'hot 
blast' idea originated 
about 1830 with 
James Neilson, a gas 
engineer of England, 
and its introduction 
revolutionized the 
blast furnace indus- 
try and made the 
highly efficient mod- 
ern practice possible. 
"This big pipe 
above our heads 
which encircles the 
furnace is the 'bustle 
pipe.' It also has to 
be lined with fire 
bricks. The hot blast 
is distributed by this 
'bustle pipe' to the 
tuyeres here — these 
L-shaped pipes 
— which shoot it directly into the furnace. Through the 
peep-holes in the tuyeres you can get a glimpse of the daz- 
zling interior of the furnace. The blast of heated air is 
causing the coke to burn fiercely there so that it melts the 




: .SJLmJkX 
JLftJfcJL 

.# M i" ■ '■ ■ _. 



Furnace and Sand Bed Ready for Iron 




60 



THE BLAST FURNACE 



61 



iron, which farther up in the furnace has been forced to 
part from the oxygen, as I explained to you." 

But now six men with a long steel bar are starting to 
break through the two or three feet of clay with which the 
"tap hole" of the monster furnace is plugged, and our in- 
formant hurries 
away. 

^* For ten minutes 
with strong sledge 
blows the tappers 
struggle to break 
through the plug of 
burned clay. Mean- 
while the monotonous 
whistle of the heavy 
blast into and 
through the bustle 
pipe and tuyeres goes 
on and the discharge 
pipes of the water- 
cooling plates empty 
into the gutter around 
the furnace bottom 
the water which has 
been circulating to 
keep the inner bricks 
from fusing. 

And now a shout 
and the strong red glow throughout the cast house tell us 
that the tap hole is open and the iron is running down 
the main channel of the sand bed. Past the plugged en- 
trances to the lateral branches runs the molten iron stream 
to the end of the cast house nearly one hundred feet distant 
where it divides, filling the laterals on each side and from 




Skip Hoist at Work. Skip Dumping into 
Hopper 




62 



THE BLAST FURNACE 



63 



them running into many open molds arranged like the teeth 
of a comb. Each of these molds is about five feet long. 
They form the ''pigs," and the laterals what are known 
as "sows." As each lateral and its molds fill, the lateral 
ahead of it is opened and the process repeated, laterals 
and pigs filling np simultaneously on opposite sides 
of the main channel till the whole cast house floor is 
filled nearly up to the furnace with the red smoking metal. 

There are few 
sights more glorious 
than the cast house 
with bed just filling 
with metal, and espe- 
cialty is it so at night. 
The strong yellow- 
red light of the flam- 
ing metal issuing 
from the furnace and 
the intense glow of 
that already in the 
bed illuminates 
everything in and 
about the building. 
But already, before 
the furnace is empty, 
the workmen are spraying with water the earliest cast pigs. 
Covering them with a light layer of sand they venture upon 
them with thick-soled shoes and break the "pigs" from 
the "sows" with sledge hammers. 

This is the old-fashioned "sand cast" pig iron. After 
remelting in the cupola furnaces of neighboring towns and 
casting into stove parts or other forms it is known as 
"cast iron"; through "puddling" in reverberatory or 
special furnaces it becomes "wrought iron"; after decar- 




Sand Cast Pig Iron 



64 NON-TECHNICAL CHATS ON IRON AND STEEL 



bonizing 



is 



treatment 
changed 



in steel 
into the 



furnaces of various de- 
wonderful material called 



sign it 

"steel." 

Pig iron is thus the intermediate or semi-raw material 

from which practically all of our various iron and steel 

products are made 
a n d the transition 
product through 
which they pass. 



But the romantic 
period of the hand- 
fed furnace and the 
gloriously beautiful 
pig beds at casting 
time are rapidly 
passing; in fact, are 
almost past. Modern 
"skip-hoists" 
carrying auto- 
matically dumped 
buckets or cars 
charge the furnace 
more economically than even low-waged laborers can do it. 
The two charging cars alternate, one filling at the bottom 
in the stock house while the other is dumping through the 
double bell at the top of the furnace. Furnaces are now- 
tapped by power-driven drills which make quick work of a 
formerly difficult operation. Instead of running it into the 
sand bed, the molten iron from the furnace is nowadays 
run into ladles alongside the cast house as is the cinder 
which was described above. If the metal is to be made into 
pigs it goes to the pig casting machine, where the traveling 
iron molds very quickly convert the entire cast into "chilled 




Machine Cast Pig Iron 




65 



66 NON-TECHNICAL CHATS ON IRON AND STEEL 



cast" pigs. At the top of the incline these pigs which have 
been cooling under sprays of water fall from the traveling 
molds into railroad cars below which deliver them to the 
consumer. 

In large steel works the greater part of the molten iron 
is not cast into pigs at all but while yet molten is directly 
charged into the open-hearth or Bessemer furnaces which 
convert it at once into steel of which the greater part is 
made into plate, rails, or other shapes before being allowed 

to cool. Even the gas 
is recovered nowa- 
days. Its journey 
through the ' ' dust ar- 
rester" rids it of 
most of its dust, after 
which niters and 
washers clean it thor- 
oughly. That not re- 
quired for the heat- 
ing of the stoves is 

Upper End of Casting Machine Where Pigs Are used f OT firing the 

Dumped from Traveling Molds into ot PaTri hmlpr* flhrmt 

Railway Cars Sieam DOlierS aDOUl 

the plant and as fuel 
for batteries of huge gas engines which in large plants 
have been installed to generate low-priced electric current. 

It should be noted that in modern practice iron is mined, 
loaded, transported to the furnaces, unloaded, charged and 
made into pigs or converted into steel and even into the 
finished products with practically no hand labor, all opera- 
tions being performed by machinery. 

Though a "direct" process for converting the ore into 
wrought iron or steel has been long sought, a method has 
never been found, except that used in the very small way 
followed by the old iron-workers with their crude furnaces. 




THE BLAST FUKNACE 



67 



It has always proved commercially advantageous to make 
pig iron in the blast furnace as an intermediate step and 
then by a second step convert it into wrought iron, steel, 
etc. So the ore is brought from the mines to the fur- 
nace, the coke and limestone arrive from another region, 
and batteries of huge blast furnaces through the country 
make from them the pig iron. 

The chemical laboratory plays a very important role in 
iron making. Analyses made of each car or boat load of 

Blast Furnace Data and Annual Pig Iron Production 





Average 
Height* 
of Blast 
Furnace 


Average 
Cu. Ft. 
Capacity 
of Blast 
Furnace 


Average 

Daily 

Output 

in Tons 

Each 


Tons Pig Iron Produced During Year 


Year 


United States 


Great Britain 


Germany and 
Luxemberg 


1850 


30' 

70' 

90' 
100' 
90 to 100' 
90 to 100' 
90 to 100' 
90 to 100' 


2000 

8200 
18200 
24000 
24000 
24000 
24000 
24000 


29 

il7 
360 
600 
600 
600 
600 
600 


565,000 

920,000 

1,865,000 

3,835,000 

9,000,000 

13,790,000 

23,000,000 

27,300,000 

30.000,000 

31,000,000 






1860 






1870 
1880 
1890 
1900 
1905 
1910 
1912 
1913 


5,963,000 
7,749,000 
7,904,000 
9,003,000 
9,746,000 

10,380,000 
9,037,000 

10,654,000 


1,391,000 

2,729,000 

4,658,000 

7,550,000 

10,988,000 

14,495,000 

17,869,000 

19,292,000 



* No advantage has been found in furnaces having a height of over 1 10 feet. 

ore by the furnace chemists representing the buyer must 
check very closely the analyses made by the mine chemists 
for the seller, as the price of every ton of ore is based on 
its iron and its phosphorus contents and the percentages 
of certain other constituents present. In calculating the 
"burden" or charges for the furnace, each of these con- 
stituents is estimated in pounds actually present per 
charge, losses or gains during the journey through the 
furnace are allowed for, and by combining the various 
ores the charges are so made up that the resulting iron 
will be of certain desired composition. The closeness 



68 NON-TECHNICAL CHATS ON IRON AND STEEL 

of actual composition obtained to calculated results is 
startling. 

Truly this is an age of efficiency. 

Though technical information and statistics are not to 
be inflicted upon our readers to any extent in this series 
of articles, it may not be amiss to give one table of interest- 
ing figures which show the increase in height and capacity 
of furnaces from 1850 to the present time. During this 
period the annual production of pig iron in the United 
States has risen from 565,000 to 31,000,000 long tons (2240 
pounds). It will be noted that since 1887, when we passed 
Great Britain, the United States has been the champion 
pig iron producer of the world. 

The record production of a single blast furnace to date 
was that of one of the United States Steel Corporation's 
furnaces at Duquesne, Penn., which produced 900 tons of 
pig iron in one day. 



CHAPTER V 
A GENERAL GLIMPSE AHEAD 

We have arrived at the parting of the ways. From the 
vast beds of iron ore, the coal fields and coke ovens, and 
from the quarries of limestone, all roads have led to the 
blast furnace. This we have visited and we now know how 
pig iron is made. 

From this point the several paths diverge. One by one 
we are to follow them to get acquainted with the interesting 
country which they traverse and the regions to which they 
lead. However, before choosing any one of these paths for 
our first trip, it will be to our advantage to pause, to study 
for a moment our position and get a general view of the 
country ahead of us. We should know the relative loca- 
tions and importance of the places we are going to visit, 
for only by getting a comprehensive idea of the general 
plan of this ferrous (meaning iron) world, can we under- 
stand to the best advantage the position of each of the 
main products, wrought iron, steel, cast iron, malleable 
iron, etc., and acquire a satisfactory knowledge of them. 
In the last chapter pig iron was called the intermediate 
stage between the ore and the finished iron product, and 
such the sketch given shows it to be. It is only as an inter- 
mediate product that pig iron has value, for nowhere in 
the commercial world has it a purpose except as a material 
to be chemically and structurally transformed into other 
materials which may themselves be used without further 

69 



70 NON-TECHNICAL CHATS ON IRON AND STEEL 



rr"T" 



transformation. It is desirable that we fully realize the 
position of this very important semi-raw material, pig 
iron, before passing on to the study, one at a time, of the 
refined ferrous products which are susceptible of direct 
use in our commercial life. 

From Table A (page 71) it will be seen that from blast 

furnace metal 
several well- 
known prod- 
ucts are form- 
ed by the vari- 
ous processes 
of refinement. 
Each of these 
methods of 
purifica- 
tion may be 
said to result 
in a certain 
general com- 
position and 




Electric Arc, Microscope, and Camera, Part of 
Metallographic Apparatus 



structure 
which give to 
the material formed its character and properties. 



The Metallographic Method of Classification 



By aid of the microscope it is possible actually to look 
into the structure of these materials. 

By cutting in any direction through a piece of metal or 
alloy, polishing the surface exposed very clean and smooth 
and then etching (corroding) slightly with acid, the exposed 
grains of the metal may be seen when sufficiently magnified. 



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72 



A GENERAL GLIMPSE AHEAD 



73 



Not only may the grains of metal be seen, but certain of the 
other constituents which are present are visible. Photo- 
graphs, also, can be taken by attaching a camera to the 
microscope. This method of analysis, which is known as 
"metallography," has proved as valuable an aid to the 
metallurgist as it proved to the geologist when applied to 
the study of rocks and geological specimens. 

The metallography of wrought iron, cast iron, malleable 
iron and steel differentiates them to us with considerable 
accuracy, as is shown 
by a glance at the ac- 
companying photomi- 
crographs, as photo- 
graphs taken through 
the microscope are 
called. 

For our immedi- 
ate purpose of gain- 
ing a general knowl- 
edge of the relative 
positions of these 
products, this method 
of analysis probably machine for determining strength of iron 

. i ti i and Steel Bars 

cannot be excelled. 

After the processes of manufacture of these materials 
have been taken up one by one in later chapters, the photo- 
micrographs will be even better understood than now, as 
will the differences of chemical composition and physical 
properties of the alloys, such as strength, hardness, brit- 
tleness, forging quality, etc. The photomicrographs are 
given at this time to show that the materials are struc- 
turally very different and to aid in the general classifi- 
cation. 

To make them comparative, all have been taken at the 




74 NON-TECHNICAL CHATS ON IRON AND STEEL 



same magnification of seventy diameters; i.e., the micro- 
scope has made everything shown just seventy times as 
large as it actually was in the alloy. 

As stated before, the alloy pig iron normally contains 
from 3 to 5^ per cent of carbon. This was absorbed dur- 
ing the journey through the blast furnace. As long as the 
iron was molten all of this carbon was in the "combined" 
form ; i.e., in chemical combination with the iron itself. 
Cold iron, however, cannot retain in the chemically com- 
bined form as much 
carbon as does mol- 
ten iron, so, during 
the solidification and 
cooling of the alloy, 
more or less of its 
carbon was precipi- 
tated, i.e., thrown out 
of solution and from 
chemical combination 
with the iron, the 
amount depend- 
ing mainly upon the 
speed of the cooling. 
It appeared then as the "free" carbon, (crystalline graph- 
ite) which remained distributed throughout the alloy and 
may be seen as the jet black flakes in photomicrograph 
No. 198. 

Every pure metal is supposed to be composed of crystals 
or grains which would have been of the true cubic form if 
the severe internal pressure during solidification and cool- 
ing had not distorted them. 

Photomicrograph No. 99b represents quite well a pure 
metal. It is that of an extremely mild steel made by special 
methods in the open-hearth steel furnace. It is so highly 




No. 198. Photomicrograph of Sand Cast Pig 

Iron. The Thick Black Lines Are 

Graphite Flakes 



A GENERAL GLIMPSE AHEAD 



75 




NO. 



yyb. open-Hearth Iron. Probably 
Purest Commercial Iron Product 



refined that it can hardly be called steel at all but is often 
called "open-hearth iron" or "ingot iron." It is probably 
the purest iron on the 
market in commercial 
quantities to-day. 
While in the chemical 
laboratory iron of 
considerably greater 
purity can be made, 
for a commercial 
product this is re- 
markably pure, sel- 
dom containing more 
than 14 per cent of 
elements other than 
the metal, iron. 

The boundary lines of the crystals or grains may be 
plainly seen. Each grain should show practically white. 
The dark parallel 
lines, the clots, and 
the grayish portions 
result from inequali- 
ties in the polishing 
and etching. 

After noting the 
appearance of photo- 
micrograph No. 99b, 
which is of a nearly 
pure iron, one need 
have no difficulty in 
realizing that pig iron 
and the steels are 
alloys and not simple metals. The truth is that of all al- 
loys some of the well-known iron products which we are 




No. Id. Section of Wrought Iron Cut Length- 
wise of. the Bar. Black Patches and 
Filaments Are "Slag" or "Cinder" 




76 



A GENERAL GLIMPSE AHEAD 



11 



studying are by far the most complicated, much more so 
than are the nonferrous alloys, which include the brasses, 
bronzes, babbitts, German silver, etc. 

This should not worry us, however, for we shall not at- 
tempt to follow them into their complications. 

The important point just now is to observe the crooked 
black flakes of crystalline graphite in this photomicrograph 
No. 198. It is largely because of these flakes of brittle, soft 
graphite that pig iron and the cast irons are so fragile. 
One has no difficulty 
in realizing that these 
flakes, which cut in 
every direction 
through the metal, 
make it structurally 
weak, especially to- 
ward a sudden blow. 

No. Id shows a 
typical section of 
wrought iron cut 
lengthwise of 
the rolled bar. It 
will be noted that, as 
in photomicrograph No. 99b, there are no graphite flakes. 

In the process of wrought iron manufacture practically 
all of the carbon of the original pig iron is burned out, 
leaving little besides the iron itself and some viscous cin- 
der or slag. In the rolling or hammering out of the result- 
ing white-hot ''bloom," the slag inclosures which remain 
after the squeezing process are extended lengthwise 
through the bar. Upon observing with the microscope any 
prepared section of wrought iron which has been cut length- 
wise of the bar the filaments of slag may be plainly seen, 
all parallel or practically so. When such filaments of slag 




No. 3b. Steel Containing .10 Per Cent op Car- 
bon. The Carbon is in the Black Patches 



78 NON-TECHNICAL CHATS ON IRON AND STEEL 




No. 22c. Steel with .50 Per Cent of Carbon 



can be discerned in a longitudinal section it is practically 
an absolute indication that the material in question is 

wrought iron. 

Photomicro- 
graph No. 3b is that 
of mild steel contain- 
ing .10 per cent (1/10 
per cent) of carbon. 
Here we have neither 
the graphite flakes of 
No. 198 nor the slag 
filaments of No. Id. 
We can plainly see 
the boundary lines of 
the grains. The ir- 
regular dark patches which are evenly distributed through- 
out are the defining features of steel. In what might 
be called a chemical-mechanical combination, these dark 

patches contain all of 
the small percentage 
of carbon which gives 
to carbon steel its 
definite properties. 

During the manu- 
facture of this alloy 
all but a small 
amount of carbon is 
eliminated by burn- 
ing it out, as happens 
with wrought iron. 
But the steel is mol- 
ten or fluid when fin- 
ished and the slag which has been formed floats on top 
and is also eliminated, which does not occur with wrought 




No. 3<ia. Steel with 1.98 Per Cent op Carbon 



A GENERAL GLIMPSE AHEAD 



79 




No. 74. 



Gray Cast Iron. The Crooked Black 
Lines Are Graphite Flakes 



iron, which is thick and pasty at its finishing temperature. 

Therefore, steel contains no graphite and no slag but has 
only the small per- 
centage of carbon 
which was purposely 
put back to give to it 
its valuable proper- 
ties. 

Photomicro- 
graph No. 22 is typi- 
cal for steel which 
contains .50 per cent 
(y 2 per cent) of car- 
bon. The irregular 
patches contain- 
ing the carbon are 
much larger and more frequent. It will be seen, there- 
fore, that through metallography the various iron alloys, 
to a considerable extent, may be analyzed as well as 
classified. 

• Photomicro- 
graphs Nos. 74 and 
92d represent soft 
and stronger grades 
of ordinary gray cast 
iron respectively. It 
will be noted at once 
that both much re- 
semble pig iron in 
structure, as of 
course they should, 
for simple remelting 
in the cupola does not effect much modification in compo- 
sition or structure. 




No. 92d. Semi-Steel, a Stronger Gray Cast Iron 



80 NON-TECHNICAL CHATS ON IRON AND STEEL 




No. 132. Gray Cast Iron 200 Years Old 



Occasionally castings are made from molten iron direct 
from the blast furnace, but such practice is not very satis- 
factory and is little 
done. It forms prob- 
ably the only excep- 
tion to the statement 
made above that pig 
iron has no useful 
purpose in the com- 
mercial world ex- 
cept as something to 
be transformed by 
some refining process 
into another ma- 
terial. 

The remelting for 
the well-known cast iron is usually of such selected brands 
of pig iron and cast scrap as will produce cast iron best 

adapted to the pur- 
poses intended. The 
resulting alloy still 
contains 3 per cent 
or 3y 2 per cent of 
carbon. 

No. 132 is interest- 
ing. It is a photomi- 
crograph of a piece 
of cast iron which is 
approximately 2 
years old. From the 
standpoint of the 
metallurgist it is the 
same as other photomicrographs of cast iron, the difference 
in appearance resulting probably from casting conditions, etc. 



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No. 109. Malleable Cast Iron Before 
Annealing 



A GENERAL GLIMPSE AHEAD 



81 



Malleable cast iron is made much as is gray cast iron ex- 
cept that it is brought to such a composition that sections 
of castings made from the melt show a white fracture when 
broken. Castings of gray iron of course show a gray frac- 
ture. The former are extremely hard and are as brittle as 
glass until they have gone through a careful long anneal 
or heat softening process. By maintaining them at cherry- 
red heat away from air for sixty hours or more and cool- 
ing slowly, they become ' ' malleable ' ' ; i.e., not brittle at all 
but capable of con- 
siderable distortion 
without cracking. 

From the view- 
point of malleability, 
malleable iron may 
be considered to oc- 
cupy a position be- 
tween gray cast iron 
and steel. 

Photomicro- 
graphs Nos. 109 and 
35 are those of mal- 
leable iron before 

and after the annealing treatment. The former shows the 
typical structure of white cast iron, while the latter plainly 
shows the minute lumps of pure carbon and the surround- 
ing grains of pure iron metal, the two having become di- 
vorced through the annealing process. Note that the large 
amount of carbon in this, the "temper carbon" form, does 
not make the alloy brittle through cutting of the grains as 
does the crystalline graphite form of carbon. 

The above gives very briefly the most essential points in 
the classification of the irons and steels from the struc- 
tural standpoint. True it has not entered into the vast 




No. 35. Malleable Cast Iron Annealed 



82 NON-TECHNICAL CHATS ON IEON AND STEEL 



complications of the higher carbon or tool steels which are 
those which will take a "temper"; i.e., the tool steel's 
quality of hardening by quenching in water from a cherry 
red heat. The simpler points of these will be taken up later. 
But enough has been given that we now understand some- 
thing of the relative positions of the great main products, 
some reasons therefor, and their general structures. 

It has been seen that their micrographs quite definitely 
differentiate them and probably no one will have difficulty 

in recognizing and 
naming such speci- 
mens. As testing this 
it may be interesting 
to note photomicro- 
graph No. 8. Two 
different iron alloys 
made up the material 
from which this pho- 
tomicrograph was 
taken. Apparent- 
ly the bar was one 
made by heating and 
rolling together 
scrap metals. Such 
material is on the market. The photomicrograph shows 
that some of the scrap used was wrought iron and some of 
it mild steel of about .08% carbon. 




No. 8. Bar Rolled prom Scrap ; Contains Both 
Wrought Iron and Steel 



Classification by Chemical Analysis and by Physical Tests 

So far not much has been said about composition except 
that upon it to a great extent depends the structure and 
physical properties of the alloy. Composition and physical 
characteristics as well as structures are necessary to a fair 



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84 



A GENERAL GLIMPSE AHEAD 85 

understanding of the subject. There is given therefore, 
a table showing approximate comparative values of chemi- 
cal compositions and physical properties of the alloys under 
discussion. 

It should be distinctly understood that the figures given 
in Table B are approximate only and are intended to be 
average, or rather, perhaps, typical. 

There are all sorts of conditions which in practice modify 
the figures given in the table, and criticism may be main- 
tained justly against some of the too specific statements 
which here it was necessary to make. The classification 
is given with considerable hesitation and only because, ar- 
ranged in this way, it brings out existing relationships 
which otherwise would escape notice and which we cannot 
afford to overlook. 

But please do not gain the impression that these alloys 
are divided into distinct classes. There are no dividing 
lines at all. One group merges into the next so gradually 
that it is impossible to tell where the one ends and the 
other begins. 

It is to be hoped that no one will make himself miser- 
able by trying to digest these rather formidable figures of 
Table B all at one sitting. They are given mainly for com- 
parison and for reference. It is suggested that after not- 
ing carefully the similarities and differences to which at- 
tention is called, they be reserved until the processes of 
manufacture of the various alloys are taken up one by 
one. Reference to these figures on those occasions should 
be profitable. 

The main points to be noted at this time are : 

1. Open-hearth iron is practically pure iron, having no 
constituents or slag inclusions which materially affect its 
properties. 

2r Wrought iron, for all practical purposes, is pure iron 



86 NON-TECHNICAL CHATS ON IRON AND STEEL 

except for its content of slag. It is the only one of the iron 
family which does normally contain slag. 

3. Neither open-hearth iron nor wrought iron contains 
carbon in appreciable quantities. 

4. The distinguishing and active element of the steel 
family is carbon. With increase of carbon the hardness of 
the alloy increases as does its tensile strength, but the 
ductility (elongation or stretch) decreases. 

. 5. Other conditions being equal, the more carbon the 
alloy contains the more easily it melts; i.e., at lower tem- 
perature. So the purer irons such as open-hearth iron, 
wrought iron, and mild steel (i.e., steel with low carbon, 

Table C — Percentages of the so-called "Metalloids" by Weight and by Volume 





Silicon 


Man- 
ganese 


Sulphur 


Phos- 
phorus 


Total 
Carbon 


Iron* 


Total 
Metalloids 




Wt. 


Vol. 


Wt. 

.70 
1.00 
.50 
.50 
.40 
.02 
.08 


Vol. 

.7 
1.0 
.5 
.5 
.4 
.02 
.08 


Wt. 


Vol. 


Wt. 

.75 
.35 
.17 
.04 
.03 
.01 
.15 


Vol. 


Wt. 


Vol. 


Wt. 


Wt. 


Vol. 


Gray Cast Iron .... 


2.50 
1.75 
.70 
.30 
.05 
.03 
1.20 


10.0 
7.0 
2.8 
1.2 
.2 
.1 
5.0 


.09 
.10 
.15 
.05 
.04 
.01 
.01 


.36 
.40 
.60 
.20 
.16 
.06 
.04 


3.2 

1.5 
.7 
.17 
.13 
.06 
.65 


3.45 
3.20 
2.75 
.35 
.10 
.02 
.05 


12.1 
11.2 
9.6 
1.2 
.35 
.07 
.17 


92.5 

93.6 
95.7 
98.8 
99.4 
99.9 
97.7 


7.5 
6.4 
4.3 
1.2 
.6 
.1 
2.3 


26.4 
21.1 


Malleable Cast Iron. 
Cast Steel 


14.3 
3.3 


Mild Steel 


1.2 


Open-hearth Iron . . 
Wrought Iron 


.3 
5.9 



* These alloys contain small amounts of other elements so these percentages of iron are a little 
high, though approximately correct. Note the purity (high percentage of iron) of the open-hearth 
iron. 

usually under 0.15 per cent) have relatively high and the 
cast irons lower melting points. 

6. In the cast irons, the carbon occurs not in one only 
but in two different forms ; i.e., as graphitic carbon, com- 
monly called graphite (Gr. C.) and the combined form (C 
C). The sum of these is usually between 3.00 per cent and 
3.50 per cent. It is not so much the total amount of the car- 
bon that causes the differences in structure and physical 
properties which have been noted in 1 and 2 and in 16 and 
17 above, as it is the relative proportions in which these 
two varieties occur, 




87 



88 NON-TECHNICAL CHATS ON IRON AND STEEL 

7. No one knows just when, with increase of carbon, 
steel ceases to be steel and becomes white cast iron. There 
is no definite dividing line either in chemical or physical 
properties. The changes are extremely gradual through- 
out the scale. Aided by the microscope, modern physical 
chemistry has disclosed the fact that alloys of iron with 
carbon "freeze" from molten to solid condition accord- 
ing to two different laws. The change from one to the 
other occurs somewhere between 1.7 per cent and 2.2 per 
cent of carbon as is described in Chapter XXII. This is 
our only basis for calling alloys with less than 2 per cent 
of carbon, steels, and those with greater amounts, cast irons. 

8. For our immediate purposes the other "metalloids" 
or constituents are of secondary importance and will not 
be taken up now. From this it must not be understood that 
they can be slighted by the metallurgist and furnace man in 
his work. They cannot. Every one of them is of impor- 
tance and must be accounted for in the final product or 
trouble results. 

Volumetric Analysis of the Iron Alloys 

There is a way in which we may visually get a 
very intimate idea of the relative composition of these 
alloys. 

The cabinet of which a photograph is given is partitioned 
into four sections. Each one of these contains a bar and 
six specimen jars. As you may or may not be able to read 
from the labels, the bars, all of exactly the same size, are 
soft cast iron, semi-steel (a stronger cast iron), annealed 
malleable iron and cast steel. The six jars above each bar 
contain the exact amounts of the various constituents other 
than iron which are in the bar beneath. 

As none of the constituents except manganese are as 



A GENERAL GLIMPSE AHEAD 89 

heavy as iron, their volumes per unit of weight are cor- 
respondingly greater. Putting it into approximate figures 
we have the percentages by weight and by volume shown 
in Table C. 

This means, of course, that of the cast iron plates of your 
cook stove or steam or water radiators fully one quarter 
(26 per cent by volume) is not iron at all but brittle sub- 
stances of little or no strength. These elements, silicon, 
sulphur, phosphorus, and carbon, are commonly called 
"metalloids." While the first three named are not in 
"free" form in the alloy and therefore allow of some doubt 
as to just the space they require, we have good rea- 
son to suppose that the figures given are not far from 
correct. 

With such a volume of weakening constituents and par- 
ticularly with the graphite flakes cutting through and sepa- 
rating the iron grains as the photomicrographs show, can 
one wonder that cast iron is fragile — more so than steel or 
wrought iron? 

To sum up, naming only the most familiar alloys and the 
two or three qualifying features of each which stand forth 
with particular boldness, we have : 

Pig Iron — Very High Carbon. Brittle. 

Gray Cast Iron — High Carbon. Brittle. 

Malleable Cast Iron — High Carbon. Made Malleable by 
Annealing. 

Wrought Iron — Slag. Little or no Carbon. Very Malle- 
able without Annealing. 

Mild Steel — Very Low Carbon. No Slag. Very Malle- 
able without Annealing. 

Carbon Tool Steel — Medium Carbon. No Slag. Of Me- 
dium Malleability. 

So steel which is not called "iron" at all is a very pure 
metal in comparison with gray and -malleable cast iron and 



90 NON-TECHNICAL CHATS ON IRON AND STEEL 

usually has a larger percentage of the chemical element 
iron from which all are derived, than has the well-known 
wrought iron itself. 



CHAPTER VI 
WROUGHT IRON 

We of America, and especially of the West, never have 
been particularly devoted to the study of our genealogies. 
However, it is likely that most of us at one time or other 
in our mind's eye have seen that little country town back 
in Massachusetts or New York State, whence came our 
forebears. Since those days of long ago, when, with you 
upon his knee, grandfather waxed reminiscent and related 
tales of his boyhood, haven't you many times wished that 
Father Time could carry you back with him a hundred and 
fifty years and allow you for a few hours to walk among 
those good people with their quaint dress and customs'? 
How interested you would be in the relatives and friends 
whose queerly transcribed verses, bearing date of a 
century and a half ago, adorn the yellow pages of your 
great aunt's autograph album, which is one of your treas- 
ures! 

To the present rather unsentimental world we admit of 
much the same sort of reverent feeling as we traverse the 
paths, centuries old, of the wrought iron region. Here is 
something which links us with the antiquities and we ' ' take 
off our hats and tread lightly" over the lands and the 
centuries in and through which this primal material, 
wrought iron, has been produced. 

91 



92 NON-TECHNICAL CHATS ON IRON AND STEEL 



But we come back to a plain statement of the case. Let 
not the fact be overlooked that it is wrought iron which in 
some form or other has been made during the forty or more 
centuries that iron has been known. It undoubtedly was 
the pioneer of the iron family and through all of the cen- 
turies it has maintained its importance. From it as a base 
during the earlier centuries were made the steels for which 
the ancients were so famous, and similar practice has pre- 
vailed from those early times up to the present day. 



We say that 
the ancients was 
ety of what we 
iron, for it ful- 
principal 




the iron made by 

in reality a varie- 

now term wrought 

filled three of the 

requirements for 

wrought iron, viz., it was not 

necessarily melted during 

production, it was a malleable 

metal, and it contained cinder 

or slag, but practically no 

carbon. 

Early iron and steel, of 
course, were comparatively 
rare, so much so as to be 
available only for implements 
of war and for particular pur- 
poses. Moreover, all of the steel made was of the high car- 
bon, hard variety, none of it being of the low carbon sort 
which we know as the soft or mild steels. The latter have 
all come since the invention of the Bessemer process in 
1855 and the Siemens-Martin (the open-hearth) process of 
a few years later. 

As you will remember the next development in the 
iron industry was the use of the larger blast furnace and 
much more fuel, with higher temperatures and the pro- 



Wkought Iron Bar 
Steel has no "fiber" and 
can not be split in this 
way. 



WROUGHT IRON 



93 



duction of cast iron which, by reason of the absorption 
of considerable carbon from the fuel, was fluid enough 
to run out of the furnace. And, as you also know, 
this blast furnace metal has come 
to be the great intermediate prod- 
uct in what has come to be known 
as the Indirect Process of making 
iron and steel. 

As pig iron contains Sy 2 % or 
more of carbon, while wrought iron 
has none or comparatively little of 
this embrittling element, any proc- 
ess for converting the pig iron into 
wrought iron must eliminate the 
carbon. 

Following the advent of pig iron 
as a commercial product several 
furnaces and processes were devel- 
oped to turn it into wrought iron. 
All of these were based upon the 
elimination of the carbon by oxida- 
tion, which means the burning of 
the carbon in presence of oxygen 
of the air. 

The best known ones were the 
Walloon or Swedish Lancashire 
process, the South Wales process, 
the Finery Fire, the Running-Out 
Fire and the Charcoal Finery or 
Knobbling process. The Walloon 
furnace, largely used in Sweden, is shown in the illustra- 
tion on page 94. 

While by the process generally used to-day wrought iron 
is more easily and cheaply produced, it must be said that 




Pickling in Weak Acid Ex- 
poses the "Fibers" op 
Wrought Iron 



94 NON-TECHNICAL CHATS ON IRON AND STEEL 



by the processes above named lias been made as fine iron 
as has ever been produced. The Sheffield manufacturers, 

whose high-grade steel made by 
the crucible process, is so widely 
and favorably known for cutlery, 
tools, etc., in many cases yet de- 
mand the Walloon process iron 
made from high-grade Swedish 
ores as the starting point for 
their product. 

In these furnaces which con- 
sisted mainly of a shallow hearth 
filled with glowing charcoal, with 
tuyeres for blast supply, the pigs 
of iron were heated until molten. At high temperatures 
the metalloids of pig iron will readily burn in a blast of air. 
After the air blown 




Bar Iron Will Stand Severe 

Bending Even After It 

Has Been Nicked 




over and upon the 
molten metal has 
burned out most of 
the carbon, the main 
metalloid, the melt- 
ing point of the puri- 
fied metal becomes so 
much higher that the 
heat of the furnace is 
not sufficient to keep 
it molten. It becomes 
more and more pasty 
and stiff therefore. 
This is what the iron 
maker calls "coming 
to nature." It is the signal that the carbon is about gone 
and that he must be careful or the iron will suffer in qual- 



Swedish Walloon Furnace 

One of several types of furnaces that preceded the 

Reverberatory. Some of them are still used. 



WROUGHT IRON 



95 




ity. At this stage he sees to it that the mass of pasty iron 
is well protected by glowing charcoal until it is removed 
to be hammered or worked into a bar. 

This in general is the process which was used from about 
the fourteenth century up to 1783 when Cort invented the 
reverberatory furnace which has since been the type gener- 
ally used. 

In the processes just referred to, all very similar, it 
should be noted that the iron was in contact with the fuel, 
which, therefore, had to be charcoal, the fuel with little or 
no sulphur. 

Charcoal was an expensive fuel, and, more- 
over, there was an insufficient supply because 

of the great destruc- ^_^ 

?////////////////'/>■■ ~~~ ^^^ 



tion of forests neces- 
sary for its produc- 
tion. Naturally the 
thing to do was to 
substitute coal, which 
was plentiful. But 
the sulphur of the 
coal spoiled the iron. 

This proved to be 
a great barrier until 1783 when Henry Cort of England 
succeeded in making wrought iron in a new type of furnace 
wherein the iron was refined in one compartment while the 
fuel was made to furnish its heat from another; i. e., the 
fuel and the metal were not in contact and the refined metal 
did not suffer from the sulphur content of the coal. 

The figure illustrating Cort's furnace plainly shows how 
this was accomplished and it represents almost as well the 
furnace used to-day. In the one hundred and thirty-three 
years that have elapsed since it was designed, his furnace 
has been changed only in certain details, and but two im- 




Cort's Reverberatory Furnace 
This is the type of furnace generally used to-day. 



96 NON-TECHNICAL CHATS ON IRON AND STEEL 




portant changes have been made in his process — the use 
of an iron bottom instead of the sand bed by S. B. Rogers 
in 1804 and the introduction of "pig boiling" by Joseph 
Hall in 1830. 

Cort's process is known as "dry puddling" and his trou- 
ble was the excessive loss of iron, due to his use of the sand 
bottom and the absence of a proper cinder. The loss was 
said to have been from 50% to 70% of the iron charged; 
i. e., it took about 2 tons of pig iron to make one ton of 
wrought iron. Because of the great demand for iron and 

the fact that he was 
using such a cheap 
fuel, coal, his process 
at that time was a 
success financially. 

But Cort did not 
stop here. He saw 
the desirability of a 
quicker and more 
economical method of 
reducing the 
"blooms" or balls of iron into bars or other finished shapes 
than the hammering process up to that time used. He ac- 
complished this by the use of power driven rolls, such as 
those shown in the cut. 

These two inventions of Cort's were epoch making, 
though of the two the more important one was the inven- 
tion of the rolls from which has developed the modern roll- 
ing mill. 

There remains to be described in a little more detail the 
making of wrought iron as practiced to-day. The puddling 
furnace used has a grate upon which is built the coal fire. 
The long flame passes over the fire wall and is deflected by 
the roof down upon the charge of pig iron piled upon the 



Early Iron Rolls 
While Cort did not originate the idea, it was he 
who first made the rolling process successful, and, 
therefore, he is given credit for the invention. 



WROUGHT IRON 97 

"fettling" or lining of iron oxide (iron ore or mill scale) 
over the air or water cooled iron plates which form the 
bottom and the sides of the hearth. 

With a long iron bar the "puddler" (the expert attend- 
ant) turns the pigs nntil they have melted down into the 
bath of slag or cinder charged and continually being 
formed by the chemical union of iron from the ore or pig 
and some of the sand and other impurities present. This 
cinder, which is largely a silicate of iron, is a protection 
for the bath of molten iron and its use prevents excessive 
oxidation and loss of metal. 

During the melting of the charge the heat is kept as 
high as possible and the molten iron is "puddled," i. e., 
stirred, by the "puddler" or his helper with a "rab- 
bler" or iron bar. In order to take out the phosphorus 
and sulphur, which for best results should be removed be- 
fore the carbon is eliminated, the heat of the furnace 
is lowered somewhat as soon as all of the pig has melted, 
and some iron oxide is mixed into the "bath" of mol- 
ten iron and cinder. Most of the phosphorus and sul- 
phur are chemically acted upon and pass into the 
cinder which covers the iron. Soon the mass begins to 
boil or seethe and small blue flames break through the 
cinder covering. This indicates that the carbon is being 
oxidized by the oxygen of the iron ore which was 
added, the oxygen, as in the blast furnace, having a greater 
"affinity" for carbon than it has for the iron. 

This "pig boiling" goes on for twenty or thirty min- 
utes, the "puddler" meanwhile "rabbling" the charge 
in order to hurry the reactions and to make sure that all 
parts of the bath of molten metal are uniformly exposed 
to the oxidizing conditions. 

Soon the metal begins to "come to nature" and little 
lumps of pure iron here and there through the bath stiffen 




98 



WROUGHT IRON 



99 




The Coal Pile and Fire Box of a Reverberatory 
Furnace 



up into little pasty balls. Some may be seen sticking 
out through the cinder covering of the bath and others must 
be torn loose from the bottom with the rabbler. This "ball- 
ling " period lasts 
from fifteen to twen- 
ty minutes, d u r i n g 
which time all of the 
iron has " come to 
nature. ' ' 

The puddler quick- 
ly separates into two 
or three white-hot 
balls the 400 pounds 
or so of spongy iron. 
These balls, full of 
and dripping with 
cinder, are seized, one at a time, with long tongs, removed 
from the furnace and rushed to the rotary squeezer through 
which they are twisted and turned, ever becoming longer 

and smaller in diam- 
eter until they emerge 
fro m the other 
and narrower side 
much compacted and 
with but little of the 
cinder which they 
originally car- 
ried. Without being- 
given time to cool, 
the blooms are seized 
and shoved into the 
"muck rolls," 
whence after a few passes they emerge as long flat bars, 
very rough and imperfect in appearance. ' 




Turning the Pigs to Insure Even Melting 



100 NON-TECHNICAL CHATS ON IRON AND STEEL 




Puddling the Melted Charge 



After shearing into short lengths, many pieces of this 
"muck bar," as it is called, are made into "box 
piles" and tied together with wires. These are charged 

into the furnace of 
the finishing mill. 
After coming to a 
white heat the box 
piles go to the finish- 
ing rolls where they 
are rolled into bars, 
rods, plates, or other 
shapes desired. By 
repeated cutting, pil- 
ing, heating, and roll- 
ing, double refined 
and other high 
grades of wrought iron are made, each repiling and rer oil- 
ing, of course, producing a more compact and better 

product. 

Wrought iron has 
a "fiber," as may be 
seen from two of the 
illustrations present- 
ed. In "coming to 
nature ' ' small par- 
ticles of iron crystal- 
lize out as they be- 
come purer. These 
measure perhaps V32" 
or y i6 " in diameter. 
As it goes to the 
squeezer the ball of "sponge" is made up of such grains 
of iron loosely welded together with the interstices filled 
with cinder. The squeezer, and later the rolls, elongate 




Considerable Cinder Overflows During the 
"Boiling" Stage 



WROUGHT IRON 



101 



the particles of iron into threads, which, welded together, 
make the bar. 

It is thought by some that films of cinder, too thin to be 
seen under the micro- 




Urawing One of the Balls from the Furnace 



scope, surround each 
fiber of i r ,o n and 
that these afford pro- 
tection from rusting 
and give to wrought 
iron the excellent 
welding quality that 
it possesses. 

Steel has no fiber 
and for this reason it 
cannot be split as 
was the wrought iron 
bar shown in the illustration of page 92. 

It will have been noticed that only small amounts of iron 
can be refined at one 
time. This, indeed, 
has been the un- 
fortunate part of 
wrought iron manu- 
facture, for it may 
readily be seen that 
production of any 
such material in lots 
as small as a quarter 
ton results in labor 
costs which are al- 
most prohibitive in 

these days of machine-made goods. Not only is the output 
of a furnace small but much skill and judgment are neces- 
sary for the production of a high-grade product. Very 




On the Way to the "Squeezer" 



102 NON-TECHNICAL CHATS ON IRON AND STEEL 




Cross Section of 
a "Squeezer" 



sturdy and strong men, too, are required as puddlers, for 
the work is heavy and the extremes of heat and cold to 
which they are exposed necessitate men of rugged health. 

This material in bar iron, engine 
stay-bolts, butt and lap-welded pipe 
and certain other products has long 
held a high place. Though not as 
strong as steel, its very excellent 
welding properties and comparative 
freedom from "crystallization" and 
treacherous breakage under long 
continued vibration or sudden jar 
have fostered its application in such 
products as stay-bolts, chain-links, 
cable hooks and others where failure might have seri- 
ous consequences. Too, it is thought by many that pipes, 
sheets and other articles of wrought iron resist the corro- 
sive influences of moist air, soil, etc., particularly well. The 
cinder films in 
which the fibers 
are supposed to 
be encased are 
given credit for 
such protective 
influence. 

Though the 
product has al- 
ways been a favorite with iron users, the industry has suf- 
fered during the last sixty years by reason of the high cost 
of manufacture, which has very largely restricted the ap- 
plication of wrought iron to certain uses for which first cost 
is not a main factor. 

The production of wrought iron rails has rapidly 
dwindled since the year 1880, when they began gener- 




'Box Piles" Ready for the Re-Heatino Furnace 






7 




• ■■ « 




% ':"'« 



« & 











H S O 
X X ° 



w 



103 



104 NON-TECHNICAL CHATS ON IRON AND STEEL 




ally to be replaced by rails made from Bessemer steel. 

Of recent years, mild steel lias been the great competitor 

of wrought iron. With marvelous energy, skill, and much 

capital the manufacturers of Besse- 
mer and open hearth steels have 
adapted their products very well to 
the needs of the iron user, while the 
enormous tonnages turned out in 
short time by use of ingenious fur- 
naces and other devices has re- 
sulted in a low cost of production. 

Had any of the several mechani- 
cal puddling furnaces devised for 
the manufacture of wrought iron proved really successful, 
things might be more rosy commercially for this very ex- 
cellent material. 

According to the 1916 Statistical Report of the American 
Iron and Steel Institute, the recent yearly production in 
this country of wrought iron and steel merchant bars, plates 
and sheets, and skelp for pipe in gross tons has been : 



Cross Piling Gives Cross Fi 

bers in the finished bar 

— a Desirable Quality 





Merchant Bars 


Plate and Sheets 


Skelp for Pipe 




Iron 


Steel 


Iron 


Steel 


Iron 


Steel 


1905 


1,322,439 


2,271,162 


72,156 


3,460,074 


452,797 


983,198 


1906 


1,481,348 


2,510,852 


74,373 


4,107,783 


391,517 


1,137,068 


1907 


1,440,356 


2,530,632 


74,038 


4,174,794 


444,536 


1,358,091 


1908 


685,233 


1,301,405 


54,033 


2,595,660 


297,049 


853,534 


1909 


952,230 


2,311,301 


76,202 


4,158,144 


370,151 


1,663,230 


1910 


1,074,163 


2,711,568 


91,118 


4,864,366 


350,578 


1,477,616 


1911 


835,625 


2,211,737 


89,427 


4,398,622 


322,397 


1,658,276 


1912 


944,790 


2,752,324 


75,044 


5,800,036 


327,012 


2,119,804 


1913 


1,026,632 


2,930,977 


64,729 


5,686,308 


312,746 


2,189,218 


1914 


563,171 


1,960,460 


56,590 


4,662,656 


264,340 


1,718,091 


1915 


657,107 


3,474,135 


20,253 


6,057,441 


262,198 


2,037,266 


1916 


993,948 


5,625,598 


13,303 


7,440,677 


355,445 


2,572,229 



WROUGHT IRON 105 

There is considerable so-called wrought iron on the mar- 
ket to-day which is not truly wrought iron, by which we 
mean iron "puddled" from pig iron. 



Bushelled Iron. 

After heating a mixture of thin sheet or other soft steel 
and wrought iron scrap to a welding heat in a reverbera- 
tory furnace, it may be balled and put through the squeezer, 
muck rolls, etc., as was the true wrought iron made by 
puddling. This manipulation of scrap is known as the 
bushelling process and the product as "bushelled iron" or 
"scrap bar." By using scrap bar for the outer layers and 
old wrought iron bars cut to length for the interior, box 
piles are made, which, heated and rolled, make very good 
material, though not as good as puddled iron. Certain 
grades on the market, e. g., common bar iron, contain more 
or less of this bushelled iron, but the better grades, refined 
wrought iron, double refined wrought iron, engine and stay- 
bolt iron, are usually the pure puddled product. 

As with the latter, repeated shearing, piling, and rolling 
improve the quality. 

Bushelled iron is largely the result of an endeavor to 
reduce the cost of production of wrought iron. The ma- 
terial has a legitimate place and considerable of it is used. 



CHAPTER VII 
CEMENTATION AND CRUCIBLE STEELS 

In the early days practically the only steels recognized 
— certainly the only ones desired — were of the high car- 
bon or hardening variety. These were required for the 
manufacture of swords and other implements of war, for 
tools, etc., most of which had to have hard and sharp cut- 
ting edges. 

When softer and less brittle metal was desired, wrought 
iron was available, but in all probability high carbon steel 
was the material most largely used. 

Having but the two iron alloys and these of very differ- 
ent properties, it was not difficult to distinguish between 
them. A piece of metal could be heated to redness and 
plunged into cold water. If it became glass hard when 
cooled in this way it was thereby proved to be steel ; if still 
soft, it was iron. 

But the problem is not so simple to-day. Medium, mild 
and yet softer steels, and other alloys which have steel 
characteristics have appeared and are used in immense quan- 
tities. Their advent introduced considerable complication. 

It will be well, therefore, before taking up our subject, 
"Cementation and Crucible Steel," and the several steels 
which are to follow, to make sure that we all understand, 
as well as we may, what is "steel" as defined to-day, what 
are the best known varieties, and w T hat are their charac- 
teristics 1 

For a rough classification it is safe for us to divide the 

106 



CEMENTATION AND CRUCIBLE STEELS 



107 




Hardening a Piece of Tool 
Steel. Ready to Quench 



steel world into four general divisions as follows: 

1. The harder, high carbon steels used for tools, dies, etc. 

2. The mild and medium steels of which wire, rod, 
bar, plate, pipe and structural 
shapes for bridges, ships and "sky 
scrapers" are made. 

3. Alloy steels, to which some 
metal such as nickel, manganese or 
chromium gives definite properties 
and the name. 

4. Those other modern materials 
which are known as " self -harden- 
ing" and "high-speed steels." 

The two classes last named are 
not simple iron-carbon alloys and 

their properties are less directly derived from and do not 
so plainly depend upon carbon. Metallurgically, then, they 
are not steels in the exact former sense of the word; but 
as they do require carbon — though perhaps in lesser 

amount, are made by 
regular steel proc- 
esses, have most of 
the characteristics of 
steel and are used for 
the same general pur- 
poses, they are un- 
doubtedly entitled to 
the appellation "steel." However, to distinguish, they are 
usually termed "alloy steels." 

We are just now concerned only with the steels of classes 
one and two — the carbon steels. As explained in a previous 
chapter, these are alloys of iron with not more than 2 per 
cent of carbon. 

Carbon is the element the presence of which confers 




Bowknot Made from Piece of Steel Pipe 




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gjtt&TOM J?W* % *w* 




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WfA 





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108 



CEMENTATION AND CRUCIBLE STEELS 



109 



upon iron the ability to harden when cooled suddenly from 
a cherry-red heat, as by quenching in water or oil. If the 
steel contains less than four-tenths of one per cent of car- 
bon it has little or no hardening power under this treat- 
ment ; but steel with six-tenths of one per cent or more of the 
element, has the wonderful property of being slightly malle- 
able when in the annealed state, but extremely hard and brit- 
tle after this sudden cooling — leads a dual life, so to speak. 

At any time, hard- 
ened steel may be re- 
turned to its former 
condition of softness 
by the well known 
process of annealing, 
wherein it is reheated 
to the same cherry- 
red heat and sloivly 
cooled. 

At the will of the 
blacksmith or metal 
worker alternate 
hardening and soft- 
ening may be repeat- 
ed a great many times without apparent deterioration. 

Various degrees of hardness also, may be obtained ac- 
cording to (1), the percentage of carbon in the steel, and, 
(2) the completeness and suddenness of the cooling. 

As considerable brittleness and internal strain in the 
metal necessarily follow hardening, the hardness is usu- 
ally "tempered" or "let down" by a careful reheating to 
a much lower temperature, usually 425 to 550 degrees 
Fahrenheit. From this temperature a second quenching 
"fastens" the temper at whatever of the original hardness 
the steel retains at the temperature chosen by the smith 




Low Carbon Tool Steel (.50 Pee Cent C) 
Hardened 
(Magnification 100 diameters) 



110 NON-TECHNICAL CHATS ON IRON AND STEEL 



for the second quenching. Much of the brittleness is in this 
way relieved. The smith calls it "toughening" the steel. 
Tools so treated are much less liable to break. 

The steels that will harden (we will call them "carbon 
tool steels"), range ordinarily from the .60 per cent carbon 
variety, used for hammers, cold chisels, etc., to those con- 
taining 1.50 per cent of carbon which are selected for razors, 
scalpels, and other tools requiring high temper. Each one 
of these many grades is susceptible of a wide variety of 

temper in the hands 
of a capable man, 
who must select his 
steel and give to it 
the most desirable 
temper for the work 
for which the tool is 
designed. 

Blacksmiths and 
other tool makers be- 
come extremely pro- 
ficient in judging 
steels and the proper 
temperature at which 
each should be hardened and "drawn" (tempered). They 
judge temperatures solely by the color of the steel when 
heated. Every five or ten degree change imparts a slightly 
different shade as the steel grows hotter in the forge fire or 
cooler when about to quench. 

Observation of a good blacksmith at work and a few 
minutes' conversation with him about his "art" will give 
one greater knowledge and appreciation of the carbon tool 
steels than volumes of writings concerning them. Along 
with it will come more respect for the skill of these clever 
men whose handiwork is never exhibited in salons and 




Mild Steel Pipe (.10 Per Cent C) 
(Magnification 70 diameters) 




Ill 



112 NON-TECHNICAL CHATS ON IRON AND STEEL 

about whom the world hears little, though indebted to them 
for a great measure of its civilization and prosperity. 

What and how much would be possible without machines 
and proper tools'? 

About sixty years ago steels of much lower carbon con- 
tent appeared. They have been made softer and softer 
until we have what we now know as the ''mild" steels and 
even the almost or practically carbonless material which we 
called "open-hearth iron" or "ingot iron" in a former 
chapter. These have not the hardening property but they 
possess softness, ductility and freedom from brittleness 

which the higher carbon steels al- 
ways lack. For such real evidences 
of our Twentieth Century civiliza- 
tion as the great bridges, ships, 
buildings, etc., they are indispensa- 
ble, for they are easily cut, bent 
and otherwise worked into shape, 

Quarter-inch Mild Steel _ ... . 

plate with double Fold, and they combine pliability with 

Folded Cold Without w» • , , x i n ±i 

slightest crack sufficient strength tor the service 

intended. Such steels are desir- 
able, for when overloaded they bend before they break, 
thus giving warning of the danger. 

These mild and medium steels are of immense impor- 
tance industrially. Of the 31,000,000 tons of steel made in 
the United States during 1912 probably 99 per cent was of 
the soft and medium varieties. 

It has been said that "the exception proves the rule." 
Cementation steel is the exception to the rule which we 
gave in Chapter VI that steel is always melted during its 
manufacture. 

If a thin piece of bar iron be packed in powdered char- 
coal and heated at low red heat for some time, the metal, 




CEMENTATION AND CRUCIBLE STEELS 



113 



after cooling, will be found to have 
acquired the hardening property. 
In other words by absorption of 
carbon it will have become steel 
with all of the characteristics of 
that material. Neither the iron nor 
the carbon by which it was sur- 
rounded have melted, yet in some 
way carbon has penetrated into the 
iron and if the heating has been, 
sufficiently long, carbon will be 
found at the center of the bar. 
But always there will be more car- 
bon in the outer layers of the bar 
than in those farther inside, i. e., 
it will be found in diminishing 
amounts as we approach the center. 
Just how and when the cementa- 
tion process for making steel, to be 
now described, was discovered is 
not known. It may have been the 
result of the non-uniform working 
of the larger blast furnaces which 
were developing in Continental Eu- 
rope during the Thirteenth cen- : 
tury. From the German "natural 
steel" which was probably the 
steely product too rich in carbon 
for the wrought iron which they in- 
tended to make and much too poor 
in carbon to be the fluid cast iron 
which with the growing height and 

heat of the blast furnace they later did make, may have 
come the idea. More likely, a piece of thin wrought iron 




Shelby Seamless Steel Tub- 
ing Crushed Endwise 




114 



CEMENTATION AND CRUCIBLE STEELS 



115 



was accidentally left imbedded in glowing charcoal until it 
had absorbed some carbon. 

The first mention of cementation steel appears to have 
been by an Italian metallurgist, Vannuccio Biringuccio, 
who, in 1540, described the making of steel by heating bil- 
lets of soft iron for a long time in molten cast iron. The 
modern method, the heating of wrought iron in powdered 
charcoal, was certainly known in the sixteenth century and 
this method of cementation has been practiced in France, 
England, Belgium 




and Germany since 
the seventeenth cen- 
tury. 

E e a u m u r , the 
Frenchman, whose 
process of making 
cast iron soft by an- 
nealing bears his 
name and is still used 
in Europe, was the 
first to study and un- 
derstand to any ex- 
tent the cementation 
process. Publi- 
cation, about 1722, of his complete directions for cement- 
ing iron gave great impetus to the manufacture of steel by 
this process. Fate, however, was unkind and his own na- 
tion, France, by reason of her small production of suitable 
iron for the work, was unable to profit greatly through his 
discoveries. Sweden, England and Germany were bene- 
fited to a much greater extent. 

During the early years many were the secret and wonder- 
ful mixtures and compounds offered for this work, but of 
them all carbon in some form was the only necessary element. 



A Sheffield (England) Cementation Fdrnace 



116 NON-TECHNICAL CHATS ON IRON AND STEEL 




Finely divided or powdered charcoal or bone dust has 
been mostly used. 

Sheffield, England, steel makers, have been very success- 
ful in the manufac- 
ture of cementation 
steel. Their usual 
method is to pack flat 
strips of best Swe- 
dish Walloon iron in 
charcoal in rectangu- 
lar stone boxes about 
four feet wide, three 
feet high and four- 
teen feet long. Al- 
ternate layers of 
small-sized charcoal 
and thin iron bars 
are piled in these 
boxes until they are filled, the bars not being allowed to 
touch one another. When full, top slabs are luted on to 
the boxes to make them airtight. 

Fire is kindled in the fire-box be- 
low and the heat gradually raised 
until furnace and boxes are cherry- 
red in color. This heat is main- 
tained for seven to eleven or more 
days, depending upon the hardness 
desired, i.e., the amount of carbon 
they desire absorbed. The furnace 
is closed and allowed to cool slowly, 
which requires another seven or 
more days. 

Upon unpacking the furnace the bars are found to be 
brittle and of a steely fracture instead of the soft malleable 



Sectional Elevation 
Huntsman Crucible Furnace — Original Type 




One Type of Oil-Fired Cru- 
cible Furnace 



CEMENTATION AND CRUCIBLE STEELS 



117 



material which was put in. They have become high car- 
bon steel. 

Expert workmen are able to judge very closely the hard- 
ness of the steel by looking at the fracture and they sort the 



# 



fi 



9 



I 



bars in this way, piling bars of similar hard- 
ness together. 

Bars thus made show many blisters on the 
surface and the steel became known as "blis- 
ter steel" on this account. The reason for 
these blisters was not discovered until along 
about 1864, when the well-known English met- 
allurgist, Percy, proved that the blisters were 
caused by the chemical action of carbon on 
the slag contained in the wrought iron. The 
gases formed produced the blistering of the 
bar. That this is the explanation is proved by 
the fact that bars of mild steel or iron without 
slag do not blister. 

Blister bars heated to a forging heat and 
drawn out un- 

Ground Levfl 



derthe hammer 
or rolled into 
bar steel are 
known as 
"spring steel" 
or "plated 
bars." 

As in wrought 

iron manufacture, a cutting to length, repiling, heating, 
welding and again drawing down by hammering or rolling 
produces much more homogeneous and reliable steel. Piled 
and reworked steel of this sort became known as "shear" 
steel because blades of shears for cropping woolen cloth 
were always made in this way. 




.„ Redbrick 

■V 



t — '&lJTKbrick. 



Sectional Elevation 

Huntsman Coke-Fired Crucible Furnace- 
Modern Type 



118 NON-TECHNICAL CHATS ON IRON AND STEEL 



Many of us will recognize in the cementation process 
an extended "case hardening." Case hardening is very 
largely resorted to by iron and steel workers, who in a 
few hours can give a hardened and long-wearing thin outer 
layer of steel to a piece of iron or soft steel after it has 
been forged or machined into the desired shape. 

This shear steel was largely made and was quite satis- 
factory, until, as described before, Huntsman, a Sheffield 
clock maker, conceived the idea of melting together in a pot 

isssss. or crucible blister 

bars or bars ot 
shear steel. This he 
did to equalize the 
carbon content and 
give uniformity of 
product which had 
never been attainable 
through the cementa- 




Sectional Elevarion 

Siemen's Gas-Fired Crucible Furnace— Regen- tlOll prOCCSS alone. 

erative system From that date 

One pair of Checker- work Chambers, k. h.. is being /-i r 7A()\ f n + "U i a +1-iq 

heated by the hot outgoing flame and waste gases v 1 ' * U / I0 l R 1 S Ille 

while the other pair is heating incoming gas and Crucible prOCCSS has 
air. They are worked alternately. , . 

undergone only mi- 
nor alterations and to-day it produces the highest grades 
of steel which we have. Practically all of the high grade 
tool steels are produced by this process. 

Nor has Huntsman's form of furnace been greatly 
changed, as the illustrations prove. Though gas and oil 
as well as coal are, in many cases, used as the fuel, the gen- 
eral design of the furnace has remained the same. 

For a century crucibles were made from clay molded to 
form, slowly dried and very carefully burned. Usually 
each steel maker made his own crucibles. They could be 
used but three times, becoming so thin and tender after 



CEMENTATION AND CRUCIBLE STEELS 



119 



use for three batches of steel that they were not safe for 
a fourth. Graphite crucibles are now very largely used. 
They withstand the severe heat much better and can be 
used five or six times. The expense item for either clay 
or graphite crucibles is a large one. 

After filling with small pieces of blister or shear steel 
the crucibles are entirely surrounded by coal or coke in the 
furnace pit. 
The fire is so 
regulated that 
the steel is not 
too quickly 
melted. Fresh 
coal or coke 
must be put in 
around the 
crucibles two 
or even three 
times. 

When he 
thinks the 
steel should 
be molten, the 
expert attend- 
ant known as 

the ' ' melter ' ' quickly removes the tight fitting cover of the 
crucible and with an iron rod determines whether any un- 
melted pieces remain. 

After complete melting the steel must be "killed," else 
it will boil up in the mold upon pouring and leave a spongy 
or insufficiently solid "ingot" or block of steel. This "kill- 
ing" of steel is a rather peculiar phenomenon. It is accom- 
plished by allowing the steel to remain quiet in the furnace 
for another half hour or so. Undoubtedly the quieting is 




The Stalwart Meltees 



120 NON-TECHNICAL CHATS ON IRON AND STEEL 



the result of the escape of the gases or impurities 
which are contained in the charge, and absorption of 
the chemical element, silicon, from the walls of the crucible. 
We have met this element, silicon, before in our metal- 
lurgical journey and we will likely meet it several times 
again. To the metallurgist it is secondary in importance 
only to carbon. 

When the steel has been properly melted and killed it is 
ready to pour. An assistant lifts the cover from the melt- 
ing hole, the 
11 puller- 
o u t " seizes 
the crucible 
just below the 
bulge with cir- 
cular tongs 
and pulls it 
from the 
coke which 
surrounds 
it. The slag 
is skimmed 
off the top 
and the steel 

poured into iron molds forming small "ingots," usually 
from 2 to 4 inches square and two feet or more long. 

Every part of the process, even the pouring, must be 
done with extreme skill and care or the product suffers. 

After liberation from their molds, the ingots are heated 
and either rolled or hammered down to the sizes desired 
for tools, etc. 

As stated before, crucible steel necessarily is an expen- 
sive material both on account of high labor and crucible 
costs. For this reason, many have resorted to the process 




Pulling the Crucible 



CEMENTATION AND CRUCIBLE STEELS 



121 



used in the very small way mentioned for the manufac- 
ture of Wootz steel — the melting of wrought iron bar or 
soft steel in a crucible with carbon. 

In the Wootz process chopped wood and green leaves 
were used. Nowadays charcoal is substituted or there is 
added the proper amount of cast iron to give the desired 
amount of carbon to the wrought iron or soft steel charged. 
During the melting the iron takes up the charcoal and alloys 
with it. 

Proper 
amounts of 
silicon, man- 
ganese, and 
other bene- 
ficial mate- 
rials are also 
charged, 
which become 
either part of 
the alloy it- 
self or have a 
cleaning or 
fluxing action 
upon it. 

Steels made 

in this way are practically, though perhaps not quite, as 
good as steels made by melting together the properly se- 
lected cementation bars. The method has come to be very 
generally used on account of its directness and because it 
eliminates the long and expensive preliminary cementation 
process. 

When Bessemer and open-hearth steels made their ap- 
pearance in the market an attempt was made to use them 
instead of wrought iron as the base for high-grade crucible 




•Teeming" ok Pouring into Ingots. The Ingots Later Are 

Forged or Rolled into Bars from Which the Tools 

Are Made 



122 NON-TECHNICAL CHATS ON IRON AND STEEL 

steels. Though seemingly pure enough, apparently purer 
even than wrought iron, these metals were not able to com- 
pete with wrought iron for this purpose. For some reason, 
not yet satisfactorily explained, these new materials which 
are made in 15, 35 and 50-ton batches, when used as 
a base, do not give as high quality tool steel as puddled 
wrought iron, which is slowly and laboriously made in 
500-pound lots. Considerable of these materials are 
utilized but it is for a somewhat lower grade of crucible 
steel. 

For many years mild steels for castings have been quite 
largely made by the crucible process. They are among the 
best but the crucible and labor costs are usually too great 
to allow crucible steel castings to compete in present 
markets. 



CHAPTER VIII 
BESSEMER STEEL 

The " Manufacture of Malleable Iron and Steel without 
Fuel" was the startling title of a scientific paper read in 
1856 before the British Association for the Advancement of 
Science. This was the announcement to the world of Henry 
Bessemer 's invention of the process for making iron and 
steel which led to the greatest commercial development the 
world has seen. 

To those of us who have had little or no experience 
along manufacturing lines the announcement seems strange 
enough, but metallurgists, engineers and manufacturers 
who know how serious is the matter of fuel bills realize at 
once how revolutionary the claim of Bessemer must have 
seemed to men of those days. 

As occurs with so many new things the idea was scoffed 
at ; Bessemer 's scheme was one purporting to give ' ' some- 
thing for nothing" and — well, it could not be. 

It was ridiculous ! 

And why should it not have seemed strange when we 
consider that up to that time fuel had been required in all 
metallurgical processes. In the old Catalan furnace and 
the types that preceded it, in the Finery Fire, the Walloon 
and the several other refining furnaces fuel had to be pro- 
vided without stint. The lowest proportion that seventy 
years of experiment and practice had brought about in 
Cort's puddling process was one ton of coal per ton of iron, 

123 



124 NON-TECHNICAL CHATS ON IRON AND STEEL 



while the blast furnace required at the least four-fifths 
of a ton of coke for each ton of pig iron produced. 

Whether Bessemer, an Englishman of French descent, 
or William Kelly, an American of Irish descent, of Eddy- 
ville, Ky., first conceived the idea of the "pneumatic" proc- 
ess is a moot question. Considerable evidence substanti- 
ates the claim that the latter first hit upon the scheme and 

during the ten years 
between 1846 and 
1856 had consider- 
able success with its 
development. 
Perhaps Besse- 
mer had heard of 
Kelly 's experiments. 
There is no proof 
that he did. Whether 
he did or not, the fact 
remains that he quite 
independently and 
very fully developed 
the process in Eng- 
land, and with great 
business sagacity and 
energy made it the 
success that it is. 
As fortune has withheld from Kelly and from this coun- 
try credit which was deserved, it is desirable to tell briefly 
the part which he had in the development of this process 
that with a single furnace converts pig iron into steel at 
the rate of a thousand tons in 24 hours and first made mild 
steel available as a building material. 

In 1846 Kelly, with a brother, bought the Suwanee Iron 
Works, near Ecldyville, Ky. After about a year they encoun- 




Kelly's First Tilting Converter 



BESSEMER STEEL 



125 




Crucible with Which 
Bessemer's First 
Experiments Were 
Conducted 



tered the same difficulty that charcoal iron manufacturers 

usually have encountered — the failure of the supply of fuel. 

This difficulty Kelly, a better inventor 

than business man, apparently had not 

foreseen. His business was threatened 

unless some other way of refining his 

iron was found. 

One day while watching the operation 

of his Finery Fire he noticed that the 

blast of air from the tuyere made the 

molten iron where it impinged very 

much whiter and apparently hotter than 

the rest. Like other iron makers, he had 

always supposed that a blast of cold air 

chilled molten iron. 
It appears that Kelly was not long in surmising the 

truth. In a few days he had rigged up a crude apparatus 

and made soft iron from which a horseshoe and a horse- 
shoe nail were fashioned by a 
blacksmith. 

Being conservatives, Kelly's 
customers were not slow in in- 
forming him that they did not 
want iron made by anything other 
than the "good old process" and 
he was obliged to accede to their 
demands or lose their trade. 

Like Galileo, however, he had 
not really surrendered. In the 
woods near by he built and ex- 
perimented with seven successive 
"converters," as the furnaces are 

called in which Bessemer steel is made. 
Upon learning that Bessemer of England had been 




Fixed Converter op 1856 with 

Six Tuyeres About the 

Sides 



126 NON-TECHNICAL CHATS ON IRON AND STEEL 




Bottom Blowing Tilting Conveetee 



granted a United States patent (1856), Kelly came before 
the patent office and proved that he had several years be- 
fore used the same process. The priority of his invention 

was acknowledged, 
and a patent was 
granted to him also 
(1857). 

Financial troubles 
and finally bank- 
ruptcy handicapped 
him. However, the 
Cambria Steel Co., of 
Johnstown, Pa., be- 
came interested and let him experiment with his process 
at the company's plant. Here in 1857 he built his first ''tilt- 
ing" converter. His first public demonstration resulted in 
failure and ridicule, 
but a few days later 
he was successful. 
Steel makers bought 
interests in his pat- 
ent, which at its ex- 
piration in 1870 was 
renewed by the 
United States 
Patent Office, while 
renewal of Besse- 
mer 's patent was re- 
fused. 

The Kelly Pneu- 
matic Process Company, which was organized to oper- 
ate under Kelly's patents, built a converter at an iron 
works at Wyandotte, Michigan. Here the first pneu- 
matic process steel ever made in this country in other 




In 1858 Bessemee Erected His First Converter 
op the Form Generally Used To-Day 



BESSEMER STEEL 



127 



than an experimental way was " blown" in 1864. 

Meanwhile Alexander L. Holley, an American engineer, 
had obtained for another American company the right to 
manufacture steel here under Bessemer 's patents. He 
built a plant at Troy, New York, which began making steel 
in 1865. 

It was soon decided to merge the interests of the two 
companies and in 1866 this was done, the process thereafter 
being known as the Bessemer Process. 
During the early years of the process 
here Holley became very well known. 
As consulting engineer he designed 
practically all of the Bessemer plants 
which were built during the first ten 
or fifteen years. 

To the majority of the people of the 
United States to-day Kelly and his 
parallel part in the great invention are 
practically unknown, and thus not only 
he but the United States is without 
credit which should be ours. 

Fortunately Kelly did not entirely 
fail to profit financially as so many 
times is the case with inventors. He 
received a total of about $500,000. Bes- 
semer 's return from his process is said to have approxi- 
mated $10,000,000 and he was knighted by the British sov- 
ereign. 

More intimate details regarding Kelly and his work may 
be found in Munsey's Magazine for April, 1906, where H. 
Casson gives information which he received direct from 
several of the men who knew and worked with Kelly. 

While apparently not the originator of the process, Bes- 
semer is without any doubt entitled to most of the credit 




Even the Detachable 
Bottom — to Facili- 
tate Repairs — Was 
Thought op and Pat- 
ented by Bessemer 
—1863 



128 NON-TECHNICAL CHATS ON IRON AND STEEL 



he received. There is no proof that he had heard of Kelly's 
experiments when he began his own or that he was aided 
by Kelly's discoveries. He worked ont the details of the 
process independently, as had Kelly, and it was Bessemer 
who put it on a commercial basis. 

As has occurred with other new processes Bessemer 's 
first licensees were not particularly successful. When those 
who had bought the right to use his process had failed in 
their efforts to use it, and become discouraged as most of 
them did, he quietly bought back their rights and went 

ahead with his development of the 
process. Perhaps no man ever ex- 
hibited more perseverance in con- 
tinuing experiments and develop- 
ment under very discouraging con- 
ditions than did Henry Bessemer. 
He had faith. 

He had a genius for inven- 
tion and was thorough in his ex- 
perimental work. Practically no 
type of converter has since been 
brought out that he did not think 
of and try, and the process has 
been modified in but one or two important particulars in 
the years that have passed. 

The essential part of the Bessemer process is the blow- 
ing of air through molten cast iron to remove the metal- 
loids by which cast iron differs from steel and wrought 
iron, as has been explained before. 

This being the essential point, and at first thought the 
lack of fuel seeming so peculiar, we must describe what 
happens during the Bessemer "blow." 

Technically speaking, the metalloids are "oxidized." 
Oxidation is the chemical uniting of oxygen, generally from 




Sectional View of a Modern 
Converter Showing Air 
Duct and Tuyeres 




129 



130 NON-TECHNICAL CHATS ON IRON AND STEEL 

the air, which has 21 per cent of this element, with another 
element or material such as iron, silicon, carbon, wood, coal, 
etc. If the oxidation is slow as in the "rusting" of iron, 
the resulting heat dissipates as fast as it is generated and 
the change is hardly noticeable. If, however, the reaction 
occurs rapidly and with vigor enough, we say that the ma- 
terial "burns." The latter sort of oxidation is what we 
call "combustion." 

The affinity between the metalloids and oxygen has been 
noted by us before, but in those cases most of the oxygen 
came from a different source. 

In the wrought iron process most of it was furnished by 
the iron ore or scale which was stirred into the metal, or by 
the slag which covered the "bath." In the Bessemer, or as 
it was first known in America, "Kelly's air blowing proc- 
ess, ' ' the oxygen of the air blown through the molten metal 
directly oxidizes or burns out the carbon, silicon, and man- 
ganese. The extremely rapid oxidation of these furnishes 
the heat. 

The iron, then, furnishes its own fuel and no outside com- 
bustible is needed. 

How can this be? 

In every ton of molten cast iron there are approxi- 
mately 70 pounds of carbon, 25 pounds of silicon, and 15 
pounds of manganese or a total of about 2000 pounds 
of these metalloids in the fifteen-ton charge of mol- 
ten metal which goes into the ordinary steel plant con- 
verter. 

We know that if burned in a furnace this ton of high 
grade fuel would generate much heat. Burned inside of the 
mass of molten metal it generates exactly that same amount 
of heat and the heat is applied with such rapidity, direct- 
ness and efficiency that the molten iron which had a tem- 
perature of 2300° F., say, when charged, in nine or ten min- 



BESSEMER STEEL 131 

utes has become steel with a temperature of about 3000° 
F. simply through this rapid oxidation of its 4 to 6 per 
cent of metalloids. 

How the blast under 15 to 30 pounds per square inch is 
applied through little nozzles in the bottom of the modern 
" converter" and the several types of vessels with which 
Bessemer experimented in the course of his investigations 
are shown in the illustrations. 

Nor is it necessary that the air be blown through the 
metal. Air blown upon its surface accomplishes practically 
the same purpose, and in many of the steel foundries of 
to-day smaller converters of this "surface-blown" type are 
used for producing steel for castings. The large steel 
plants, however, use the larger "bottom-blown" converter. 
Two or three of these vessels, working with proper metal 
from the "mixer," produce an immense tonnage of steel 
each 24 hours. 

The "mixer" is quite necessary. It is a large vessel or 
furnace holding and keeping hot from 75 to 300 or more tons 
of metal from the blast furnace. It mixes and equalizes 
irons of various compositions, so that the converters have 
the advantage of uniform and hot metal with which to work. 

In addition it is made to perform a "refining" service. 
By mixing into the metal a quantity of manganese, consid- 
erable of the sulphur present (a deleterious substance) is 
removed. 

The fifteen or twenty minute blowing of 15 tons of metal 
in the big egg-shaped converters of a steel plant presents 
a spectacle which, when once observed, will never be for- 
gotten. 

One sees a little "dinky" engine - come shooting into the 
converter building with its ladle of molten iron from the 
"mixer." With America's time saving routine not a single 
minute is lost while emptying the metal into the converter, 




< a s a cJ 



132 



BESSEMER STEEL 133 

now in a horizontal position. Almost before the ladle is 
out of the way, the converter swings to the upright position 
with the blast already on, for otherwise the metal would 
flow into the tuyere holes at the bottom. 

Reddish-brown smoke and a shower of sparks come from 
the converter. These gradually develop into a flame. 

The blast shows considerable partiality in selecting for 
its first attention the metalloids silicon and manganese, in 
preference to the iron itself or any other of the metalloids 
present. After from three to five minutes half of the silicon 
and manganese have been burned out. If the temperature of 
the metal and other conditions have become right the carbon 
then begins to burn. This gives a change in the nature of 
the flame which becomes large and of a dazzling whiteness. 

The metal is hot — very hot — so much so that pieces of 
cold steel often must be dropped in to cool it somewhat. 
This is known as "scrapping" the charge. 

An experienced blower can judge through every period 
of the operation of the condition of his metal and just how 
things are progressing. 

After some minutes the flame begins to waver and later 
"drops"; i.e., there is scarcely a flame at all. This signal, 
which is very definite to an experienced man, cannot be 
lightly disregarded. Oxygen has affinity for iron as well 
as for the metalloids and it is only because of its greater 
love for silicon, manganese and carbon that it has thus 
far largely neglected the iron. With the metalloids men- 
tioned out of the way, as they are when the drop occurs, the 
iron will begin to burn. Were the "blowing" continued 
we would shortly have no iron left, but in its place a mass 
of iron oxide and slag. 

Thus we see that during the first minutes of the blow, 
more than one-half of the silicon and manganese are burned. 
The remainder of these and all of the carbon are removed 




134 



BESSEMER STEEL 135 

in the subsequent five or six minutes. At the end of this 
short blowing period we have practically pure iron. 

The metal is not yet in condition to pour well, however, 
largely because of the dissolved air and gases which it 
holds. Something akin to the "killing" of the steel which 
we observed in the crucible process must be accomplished 
or ingots from it will be spongy. And, having practically 
no carbon, it is not yet "steel." 

Bessemer, knowing that the finished steel should con- 
tain carbon, tried to stop the blow long enough before the 
drop of the flame to leave exactly the desired amount of 
this element. He found this difficult to do and therefore 
uncertain. It was found to be far better to blow until the 
drop of the flame and then put back sufficient carbon to 
give the proper composition. 

An English metallurgist named Mushet discovered that 
addition of manganese ridded the metal of injurious gases 
and oxides and what is known as "red-shortness." After 
a period of difficulty without it Bessemer acknowledged the 
necessity of manganese and adopted its use. It had be- 
fore this been used in crucible steel. 

Upon turning down the converter at the drop of the 
flame, the blast is turned off and a smaller ladle is run in 
on a track above. This brings a molten mixture of irons, 
usually known as "spiegel" or "spiegeleisen" which con- 
tains just enough carbon, manganese and silicon to give to 
the whole of the molten metal in the converter the metal- 
loids needed to make of it steel of the composition desired. 
This addition also accomplishes the " deoxidation " of the 
metal. By deoxidation we mean that the iron is re- 
lieved of the oxygen and gases which have remained as a re- 
sult of the blast. This is necessary in order to give proper 
fluidity for pouring and the best physical properties to the 
finished steel. 



136 NON-TECHNICAL CHATS ON IRON AND STEEL 



After " recarburization, " as this addition of manganese- 
silicon-carbon metal is called, the steel and slag are quickly 
poured out into a ladle waiting below from which the steel 
is "teemed" (i.e., poured), through a "nozzle" or hole in 
the bottom into ingot molds arranged on trucks on the rail- 
road track which runs through the building. 

When the molds have been filled and a strong crust de- 
velops on the steel the cars are pulled to the "stripper" 

where the 
molds are re- 
moved, leav- 
ing the white- 
hot ingots 
standing 
on the cars. 

Th e ingots 
mentioned in 
the chapter on 
Cementa- 
tion and Cru- 
cible Steel 
were usually 

Teeming the Finished Steel into the Ingot Molds SIIlRll enOUgll 

that one pot 
of 100 pounds of metal filled the mold. A four-pot furnace 
therefore produced 400 pounds. Now for the first time, 
we are talking in tonnage figures. Instead of a batch of steel 
making four 3"x3"x36" ingots of 100 pounds each, the ordi- 
nary "heat" of Bessemer steel from the 15-ton converter 
gives six or seven ingots about 18"x20"x60" in size. Each 
of these weighs about two tons. The total is 30,000 pounds. 
From the stripper the ingots go to the gas-fired soaking 
pits where the molten interiors of the ingots gradually 
solidify by cooling while the outer crusts are reheated. 



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137 



138 NON-TECHNICAL CHATS ON IRON AND STEEL 

After equalizing the temperatures of exteriors and interiors 
in this way, the ingots are white-hot again and ready for 
rolling. 

The purpose for which the steel is intended, of course, 
determines the shapes and sizes into which the ingots are 
rolled. For rails they are rolled down directly, each ingot 
making about six rails, of thirty-three-foot length. For 
most other purposes the ingots are rolled in the slabbing 
mill into billets or slabs which are of intermediate shapes 
and sizes which are reheated and further rolled down into 
axles, bars, shapes, wire or other products. 

Meanwhile the converter which we saw emptied has 
not been idle. The American steel engineer has genius 
for mechanical efficiency and all parts of a great steel 
plant are so co-ordinated that enormous quantities of 
material can be handled with not a moment lost between 
trips. Almost before the ladle of steel had swung away 
from the converter's mouth, any remaining slag was 
dumped from the converter by further tipping, the vessel 
returned to receiving position and the ladle car, back again 
from the mixer, poured in the next charge. 

Thus blow after blow is made without loss of time. 

Repairs are allowed to take no longer than is absolutely 
necessary. When the lining around the tuyeres gets too 
badly cut by the action of the air and metal the bottom is 
removed, another one is quickly substituted and the steel 
making goes on. • 

Blowers, ladlemen, cranemen, pourers, patchers, vessel- 
men, sample boys and the other workmen are relieved by 
their "partners" at the end of each shift, each man of ne- 
cessity working until relieved — twelve, twenty-four, or even 
thirty-six hours, for there must be no delay. So day and 
night, through the entire week from Monday morning at 
six, when they begin, until the next Sunday morning at six, 



BESSEMER STEEL 139 

when the plant shuts down for a brief spell, the converters 
go on turning out three heats per hour or four to five hun- 
dred per week each. 

It has been mentioned that most of Bessemer 's first 
licensees failed with the new process. The reasons for this 
were various, but one in particular was the attempt of 
many to use metal of high phosphorus content. Bessemer 
soon discovered that no phosphorus was removed during 
the "blow" and that, as phosphorus in quantity over one- 
tenth of one per cent was detrimental to steel, it was neces- 
sary to use raw material which had little of this element. 

This could be done, but it barred many pig irons other- 
wise good. Fortunately Swedish and many English irons 
had low phosphorus. Germany's vast beds of high phos- 
phorus ores, however, were useless for the purpose. 

For twenty years this situation existed, during which 
time many metallurgists endeavored to make the process 
applicable to irons which contained high phosphorus. After 
long study and many experiments the problem was solved 
by Sidney Thomas, an English metallurgist. With a cousin, 
Percy Gilchrist, he made hundreds of blows with a toy con- 
verter holding only eight pounds of iron. 

Bessemer 's linings had been of sand, clay and other 
earths which are known chemically as "acid" materials. 
By using "basic" materials such as limestone, dolomite, 
etc., for the converter lining and additions of limestone or 
burnt lime to the charge before and during the blow to 
make and keep the slag "basic," Thomas was able to make 
the phosphorus burn after the carbon had been removed. 
Therefore, a three or four minute "after blow" following 
the "drop" of the carbon flame took out the phosphorus, — 
again, with generation of heat. 

So there are two varieties of the process — the acid Besse- 
mer and the basic Bessemer, but the former, only, is used 



140 NON-TECHNICAL CHATS ON IRON AND STEEL 



in this country as we have few high phosphorus ores. The 
analogous open-hearth processes, which are next to be de- 
scribed, are both used in this country with the basic open- 
hearth greatly in the lead. 

However, the basic Bessemer process of Thomas and Gil- 



Year 



1849 
1850 
1855 
1860 
1865 
1867 
1868 
1869 
1870 
1875 
1880 
1885 
1890 
1895 
1900 
1905 
1906 
1907 
1908 
1909 
1910 
1912 
1913 
1914 
1915 
1916 



Table No. 1 
Materials Used for Rails (a) 



Wrought 
Iron 



21,710 

39,360 

124,000 

183,000 

318,000 

410,000 

445,970 

521,370 

523,000 

448,000 

441,000 

13,000 

14,000 

5,810 

695 

318 

15 

925 

71 

"230 



Bessemer 

Steel 



V 



2,280 

6,450 

8,620 

30,360 

260,000 

852,000 

959,000 

1,868,000 

1,300,000 

2,384,000 

3,192,000 

3,391,000 

3,380,000 

1,349,000 

1,767,000 

1,884,000' 

1,100,000 

818,000 

324,000 

327,000 

440,000 



Open-Hearth 

Steel 



12,160 

4,280 

3,590 

700 

1,330 

183,000 

186,000 

253,000 

572,000 

1,257,000 

\a 1,751,000 

^2,105,000 

2,528,000 

1,526,000 

1,775,000 

2,270,000 



Table No. 2 
Total Steel Made by Processes (a) 



Bessemer 
Steel 



2,679 

7,589 

10,714 

37,500 

335,000 

1,074,000 

1,515,000 

3,689,000 

4,909,000 

6,685,000 

10,941,000 

12,276,000 

11,668,000..! 



Open-Hearth 
Steel 



6,117,000 
9,331,000 
9,413,000 

10,328,000 
9,546,000 
6,221,000 
8,287,000 

11,059,000 



893 

1,339 

8,080 

110,850 

133,000 

513,000 

1,137,000 

3,398,000 

8,971,000 

10,980,000 

11,550,000 

7,837,000 



14,494,000 
16,505,000 
20,780,000 
21,600,000 
17,175,000 
23,679,000 
31,415,000 



Crucible 

Steel 



No Data 



35,180 

64,660 

57,600 

71,200 

68,700 

100,500 

102,200 

127,500 

131,000 

63,600 

107,400 

122,300 

121,500 

121,200 

89,900 

113,800 

129,700 



(a) In United States — long tons of 2,240 pounds. 

christ is credited with making Germany's great industrial 
development possible. 

The well-known "Thomas Slag" which is in demand as a 
fertilizer on account of its phosphorus content is the by- 
product of the basic-lined converter. 

An idea of what the invention of the Bessemer process 
meant to railroad development alone may be gained by 



BESSEMER STEEL 141 

studying for a moment Table No. 1. Wrought iron was 
our first material for rails, but, being very soft, it did not 
give long service. But a short time was required for Bes- 
semer steel to displace it for rails when steel became avail- 
able. The greater uniformity, strength and hardness of the 
alloy gave such excellent wearing properties that few rails 
of iron were laid after the year 1880. 

During recent years rails have been made of greater 
and greater strength and hardness to keep pace with the 
fast increasing weight, speed and frequency of railroad 
trains, steel being susceptible to much modification of prop- 
erties. 

Now it appears that Bessemer steel is giving way to 
other products which show even superior properties. 

What happened in the railroad world to a great extent 
has happened elsewhere, as the figures of Table No. 2 show. 
They are a barometer which indicates what has been our 
industrial development and our advance in civilization. 



CHAPTER IX 
THE OPEN-HEARTH PROCESS 

Bessemer 's was a wonderful process, but the time seemed 
to be ripe for great development along metallurgical lines, 
and the method of converting pig iron into steel which he 
devised soon had a competitor which was destined even- 
tually to take the lead in steel production. Many years 
passed before the tonnage turned out annually by Besse-. 
mer's process was equaled by that of the new, but as shown 
in the last chapter the Siemens-Martin or open-hearth 
process in 1907 produced the greater tonnage. It has since 
retained its lead and probably will continue to do so. 

As far back as 1845 John Marshall Heath took out a 
patent for a process for making steel patterned after the 
old puddling process. In a way he may therefore be said 
to have devised or forecast the open-hearth process, but 
because of the great obstacles that had to be surmounted 
in getting a furnace that would fulfill the requirements 
he was unable to carry out his scheme. You will remem- 
ber that in the puddling furnace the purified metal became 
pasty because of its high melting point. Because of the 
great heat required it was not until the invention of the 
regenerative system by C. W. Siemens in 1860 that the 
open-hearth process was possible. Siemen's furnace was 
the first one that could keep the iron molten. It was in 
Birmingham, England, that the first successful open-hearth 
furnace was used. 

142 




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144 NON-TECHNICAL CHATS ON IRON AND STEEL 

While not as speedy nor as prolific a producer as the 
Bessemer process and far less spectacular, the open-hearth 
has several advantages. 

The acid Bessemer was always handicapped because pig 
iron with less than 0.1 per cent of phosphorus was neces- 
sary. The majority of ores carry more than this amount. 
The basic Bessemer requires pig iron containing not less 
than 2 per cent of phosphorus. The vast quantities of 
material which contain percentages of phosphorus between 
these limits are useless as far as the Bessemer process is 
concerned. 

To be successfully used the pig iron must be further 
limited as to composition. It must have sufficient silicon, 
manganese, and carbon to give the heat required for Bes- 
semerizing, as the burning of these metalloids has to be 
depended upon for the conversion to steel and to give 
proper fluidity to the finished alloy. 

Then, too, the large amount of air forced through to a 
certain extent "over-oxidizes" the bath and some of the 
gases are mechanically retained by the steel no matter how 
complete the deoxidation. There also is loss of metal due 
to unavoidable " spitting," for the rapid streams of air 
mechanically carry some metal and slag with the flame out 
of the vessel. 

On the other hand, for the open-hearth process can be 
used pig iron of widely varied character and composition 
and, further, large percentages of low-priced steel scrap 
can be utilized in the charges; as no air is blown through 
the metal and little comes in contact with it, the conver- 
sion takes place quietly and smoothly and with much less 
loss by oxidation, the yield of steel usually being from 90 
to 97 per cent of the metal charged as against 83 to 87 per 
cent which is the yield by the Bessemer process; besides 
giving less over-oxidation and gases in the metal, the slow- 



THE OPEN-HEARTH PROCESS 



145 




Section Through Typical Stationary Open- 
Hearth Fdrnace, Showing Construction of 
Furnace, Lining, Bath and Air and Gas Ports 



ness of the conversion is an advantage, as control is very 

easy, and, when desired, samples for test may be taken. 

From his tests the 

melter can be quite 

certain Avhen he taps 

out the steel that it 

is of the composition 

desired. 

The melting in an 

open-hearth furnace 

is done largely by in- 

direct or radiated 

heat, and it is not in- 
tended that the flame shall impinge too directly upon the 

surface of the bath. 
Except during the melting down of the pig iron and other 

materials 
charged in the 
furnace, the 
flame and air 
take little part 
in t h e actual 
elimina- 
tion of the 
metalloids. 
Their main 
function is to 
furnish the 
heat neces- 
sary. Being 
used so in- 
d i r e c 1 1 y — 

mostly by radiation from the roof and walls — very great 

heat must be used and much would be wasted if special 




Boxes of Steel Scrap and Electric Charging Machine in 
Front of Charging Doors at Rear of Furnaces 



146 NON-TECHNICAL CHATS ON IRON AND STEEL 



precautions were not taken to save it. The bath must be 
kept hot enough to remain molten after purification of the 
metal, which we were unable to accomplish in the wrought 
iron puddling furnace. 

Under each end of the rectangular furnace are two cham- 
bers built up with checker-work of fire brick. These sets 
are in duplicate and each has one chamber for air and one 
for gas. 

Thus an open-hearth furnace will be seen to occupy a 
sort of hollow square, the furnace proper forming one side, 

the regenera- 
tive chambers 
two sides, 
with the chim- 
ney and flues 
the remaining 
side. "Re- 
versing" 
valves force 
the incoming 
gas and air to 
travel each 
through its respective hot regenerating chamber up through 
the ports and into the furnace where they unite and burn 
with a very hot flame. The hot gases leave through similar 
ports in the other end of the furnace and on their way to 
the chimney heat the checker-work in the regenerative 
chamber. Every fifteen or twenty minutes the valves are 
reversed and the direction of flow is changed. In this way 
the incoming gas and air are preheated and in the furnace 
burn with a very much hotter flame than would cold gas 
with cold air. No blast is required, the draft caused by 
the chimney being sufficient. 

For protection of the roof from the great heat developed 




Charging Machine with Box of Scrap Half-Way into 
Furnace 



THE OPEN-HEARTH PROCESS 



147 



and the metal of the bath from too great oxidation, the air 
ports usually are located above the gas ports. The streams 
of air, while protecting the roof from the flame, at the same 
time are prevented from directly impinging upon and too 
strongly oxidizing the metal of the bath. 

The diagrammatic sketches given show roughly a fur- 
nace, regenerative chambers, ports, etc. 

The original intention was to melt pig iron and reduce 
it; i. e., burn out the silicon, manganese, and carbon by 
action of the flame and addition of iron ore. This was 
the process worked 
out by Siemens in 
England. In France, 
P. and E. Martin al- 
tered the method by 
diluting molten pig 
iron in the Siemens 
furnace by melting 
and dissolving in it 
steel scrap. It was 
soon found that a 
combination of the 
two methods was bet- 
ter than either one alone and the open-hearth process ac- 
quired its name — the Siemens-Martin — in this way. 

In the United States about 20,000,000 tons of steel are 
made annually by the basic open-hearth process while 
only 1,100,000 tons are produced by the acid open-hearth 
process. 

The two processes are practically the same except 
that by the basic process the phosphorus as well as 
the silicon, manganese, and carbon are reduced or elim- 
nated. In order to take out the phosphorus, addi- 
tions of lime (i. e., calcium oxide or calcium carbonate) 




Charging "Hot" Metal 



148 NON-TECHNICAL CHATS ON IRON AND STEEL 

are made just as occurred with the basic Bessemer 
process. 

Should we use lime in a furnace having an acid lining, 
much of the lime, which is a "base," would react with the 
"acid" (silica) bricks of the lining, and, becoming neutral- 
ized, would not do its work. So, as in the basic Bessemer 
process, we here have to use either "basic" or "neutral" 
lining. 

The material generally used is burnt magnesium carbon- 
ate which is known as "magnesite." Dolomite, which is a 
combination of the carbonates of calcium and magnesium, 
is sometimes used. Chrome bricks, the usual neutral ma- 
terial, are rather too expensive for extensive use. The best 
magnesite comes from Austria and is usually not very 
cheap. As acid materials (those of silica or clay) are 
cheaper and mechanically stronger, a compromise is oft- 
times effected by using basic materials for the furnace bot- 
tom and acid bricks for the sidewalls and roof. A few rows 
of chrome bricks may be put in to form a neutral dividing 
line just at and above the edge of the bath where the action 
of the slag is the most severe. It also serves to keep the 
basic and acid materials apart and from reacting with 
each other. 

At the commencement of charging, limestone or some- 
times burnt lime is shoveled in upon the bottom or 
"hearth" of the white-hot furnace. 

When cold metal is charged, the pigs of iron are con- 
veyed into the furnace by the melter and his helpers by 
means of long handled flat iron tools called "peels." This 
is followed by charging some or all of the scrap or iron 
which is to be made a part of the charge. 

Even in the smaller 15 or 25-ton furnaces hand charging 
takes a great deal of time, sometimes as much as six or 
eight hours, and the labor cost as well as the heat loss is 



THE OPEN-HEARTH PROCESS 



149 



therefore excessive. Modern machine charging which re- 
quires not more than an hour is therefore highly desirable. 

During the melting down of the pig iron with the scrap 
that has been charged, the air and flame burn out about 
half of the silicon and manganese of the metal. To re- 
move the remainder of these and the carbon of the charge, 
additions are made from time to time of sufficient ore to 
keep the bath "boiling." This phenomenon results from 
the giving off of carbon monoxide gas formed from the 
oxygen of t h e iron 
ore and the carbon of 
the metal, just as 
happened when the 
puddler in the manu- 
facture of wrought 
iron used iron ore in 
his furnace. The cov- 
ering of slag which 
forms and protects 
the bath from the 
flame undoubtedly 
transfers oxygen 
from the furnace 
gases to the bath and this helps to burn out the car- 
bon. 

The lime charged unites with the phosphorus of the iron 
and takes it into the slag which covers the bath. If neces- 
sary, further additions of lime may be made from time to 
time during the melting and the "working down" (elimina- 
tion of the metalloids) of the charge. As long as the slag 
is kept basic it retains the phosphorus, but should it turn 
acid the iron of the bath would take the phosphorus back 
again. 

These reactions are all chemical, just as much so as are 




Row of Open-Hearth Furnaces Showing Pit or 
Tapping Side 



150 NON-TECHNICAL CHATS ON IRON AND STEEL 



the burning of wood and coal and the thousands of reactions 
which are brought about in chemical laboratories. 

Additions of ore are made from time to time and the bath 
rabbled.. Samples are taken now and then with a long 
handled iron spoon or ladle and these are poured into molds 
to form small bars of steel, which, after quenching, are 
broken. 

The melter has become very proficient in judging the 
composition of the metal of the bath from the fracture of 

these broken 
test pieces. 
By means of 
the samples 
taken he 
watches the 
elimina- 
tion of the 
metalloids. 
When he 
thinks the re- 
actions have 
progressed 

Open-Hearth Furnace "Tapping" I8.Y G n O U g U 

he takes a last 
sample which is rushed to the chemist who makes a hur- 
ried "control" analysis for carbon and phosphorus, the 
metal being held in the furnace meanwhile. If the results 
of this analysis show the bath to have the desired com- 
position the steel is poured. If the reactions have not 
been complete, the chemist's report shows that the car- 
bon and perhaps the phosphorus are still too high, in 
which case the charge must be still further worked 
down. 

Some melters are able to make fairly uniform and satis- 




THE OPEN-HEARTH PROCESS 



151 



factory steel without a chemist, but for best results a chem- 
ical laboratory is desirable. 

When ready to tap, the big ladle is suspended from a 
crane under the spout of the furnace. With a tapping bar 
the plug of clay is removed from the tap hole and the mol- 
ten steel gushes out into the ladle. The slag which has 
covered the bath is the last to drain out. Many times this 
will overflow the 
ladle, making a beau- 
tiful cascade as it 
pours over the sides 
all around to the 
floor beneath. Espe- 
cially at night is this 
a glorious sight. 

Recarburiza- 
tion is not done to the 
same extent as it is 
in the Bessemer 
process. As the 
open-hearth elimina- 
tion of carbon is 
slower and under so 
much better control, 
the furnace usually is 
tapped when the car- 
bon has been reduced to the percentage desired in the fin- 
ished steel. When it is necessary to add carbon it is done 
sometimes by adding pig iron to the bath and sometimes 
by throwing a weighed amount of coal or coke in the ladle 
as the steel is going in. Molten iron and steel have 
strong appetites for carbon and dissolve it very readily. 
Ferro-manganese is used to prevent red-shortness and 
to deoxidize the metal. This also is usually put into 




Teeming the Steel into Ingot Molds 



152 NON-TECHNICAL CHATS ON IRON AND STEEL 



the ladle as too much loss would occur were it added in the 
furnace. 

While the furnace is again being charged through the 
charging doors at the rear, the steel is teemed through the 
nozzle of the big ladle into the waiting ingot molds. These 
go to the stripper, to the soaking pits, and then to the rolls 
of the blooming mills just as did the Bessemer ingots. 
In the acid-lined furnace no attempt is made to reduce 

the phos- 
phorus. It 
would be fu- 
tile. There- 
fore the mate- 
rials charged 
must be very 
1 o w in phos- 
phorus and 
sulphur. 
No lime ad- 
ditions are 
made, the 
flame simply 
melts down 
the pig iron 
and scrap, the iron oxide later is added from time to time 
to keep up the boil until the test bars show that the carbon 
as well as the silicon and manganese have been eliminated 
as fully as is desired. The metal is then tapped as de- 
scribed above. 

Three or more hours are usually required to melt 
down cold charges. The elimination of the remainder 
of the silicon, manganese, and the carbon requires about 
four or five hours more. So for each heat the open- 
hearth furnace requires from eight to twelve hours, 




At the "Stripper" 



THE OPEN-HEARTH PROCESS 153 

depending largely upon the speed of charging and melt- 
ing. 

Of late years the difficulties attending the use of molten 
metal from the blast furnace in place of cold pig iron have 
been largely surmounted. The use of uniform metal from 
the "mixer," which was described in the article on the 
Bessemer process, has aided the open-hearth process also. 
Of course, when molten metal is added none of its silicon 
and manganese is reduced by the flame as occurred with 
the cold metals during the melting .down, so the molten 
metal charged is usually low in these elements to com- 
pensate. By use of "hot" (molten) metal the time nec- 
essary to produce a "heat" of steel is considerably short- 
ened. 

The first and perhaps the majority of furnaces yet build- 
ing are "stationary." Some have found it advantageous 
to construct furnaces that can be tipped to pour the metal 
into the ladle. Such are known as "tilting" furnaces. One 
furnace designer has even gone so far in a smaller type 
used for steel castings as to make the furnace removable, 
thus doing away with a ladle entirely. The big crane simply 
lifts the whole furnace out from between the housings which 
contain the ports. It is taken bodily to the molds which 
are poured directly. 

Open-hearth furnaces have been built of larger and larger 
capacity. A great many fifty-ton furnaces have been built 
and furnaces which produce eighty or more tons at a heat 
are now not uncommon. 

Furnaces of the Talbot type are built for as much as 200 
and even 300 tons of metal, but from these only part of the 
finished steel is tapped at a time, the remainder being left 
to help work down the additions of new material which is 
added to replace the steel tapped out. 

The rolling mill industry is so intimately connected with 



154 NON-TECHNICAL CHATS ON IRON AND STEEL 



and dependent upon the steel-making methods and equip- 
ment that each is designed with reference to the other. 

Bessemer steel has been largely used for the manufac- 
ture of rails, rod, wire, pipe, merchant bar, etc., while open- 
hearth steel has gone into plate, boiler tubes, structural 
shapes, billets for axles, etc. Recently it is being used for 
rails and very many of the products which were formerly 
made from Bessemer steel. 

It sh o ul d 
not be in- 
ferred from 
this that Bes- 
semer steel is 
no longer in 
demand or 
that it is not 
good steel. 
As you will 
notice from 
the table 
given in t h e 
last chapter, 

Lower Half of a "Battery" of Modern Gas Producers t 11 e prOClUC- 

tion of Besse- 
mer steel has not declined appreciably, if at all. The fact 
is that open-hearth steel production has been increasing 
at a great rate, while the production of Bessemer has re- 
mained stationary. With the growing scarcity of ores 
suitable for pig iron for Bessemerizing, the open-hearth 
process is becoming able to compete with the Bessemer 
process in the matter of cost. For some purposes the 
steel is considered to be a little more desirable, but, as is 
the case with many good things, the pendulum swings too 
far and there is no doubt that open-hearth steel is often 




THE OPEN-HEARTH PROCESS 155 

demanded and used for purposes for which Bessemer steel 
would be just as good and perhaps better. 

For many years it has been said that the Bessemer proc- 
ess is "doomed." This, of course, was because of the 
scarcity of low phosphorus ores. Just how "doomed" it is, 
it is perhaps impossible to say. Certainly it is still a very 
live process and the combining of processes, such as "du- 
plexing," will probably prolong its life. 

By the "duplex" process, molten blast furnace iron from 
the mixer is "desiliconized" in the Bessemer converter. 
Before too much of the carbon has been burned, the metal 
is transferred to a basic open-hearth furnace where the 
remainder of the carbon and most of the phosphorus is re- 
moved. By this method the advantages of the open-hearth 
and much of the speed of the Bessemer process are com- 
bined. The output of the open-hearth furnace is thus 
greatly increased. 

To-day all kinds of combinations of Bessemer, open- 
hearth, and electric furnace are being projected and it is 
difficult and likely impossible for any one to predict the 
future of any of the processes. 

Lest the metallurgical facts scattered through several 
chapters escape, let us summarize a little. Roughly speak- 
ing, the capabilities of and materials required for the proc- 
esses are as follows — the chemical symbols for silicon, man- 
ganese, carbon, phosphorus, and sulphur being used for 
brevity: 

Process Refining Capability Material Required 

~ ... _ Removes no metalloids, but .. , „. _ „ , ., 

Crucible Process. simply remelts. Very low Si., P. S. and C . 

. ., „ „ „ , ' „. ... , „ Very low P. and S. (under 

Acid Bessemer Process. Takes out Si. Mn. and C. 0.1%). 

„ . t, „ ■ Takes out Si. Mn. C. P. Very high P. (2% and 

Basic Bessemer Process. and some s over). 

a -j ^ „ ..-'„ m , j. r,. „ r, Very low P. and S. (under 

Acid Open-Hearth Process. Takes out Si. Mn. C. 0.1% of each) 

c • n u 4-v, tt, Takes out Si. Mn. C. P. _: ' ° . , 

Basic Open-Hearth Process. an( j some g Wider Variety. 

_, T , . _, „ Takes out Si. Mn. C P. TTT ., TT . , 

Electric Furnace Process. an< j g # Wider Variety. 



156 NON-TECHNICAL CHATS ON IRON AND STEEL 



In further explanation of the competition in quality of 
Bessemer and of open-hearth steels it should be understood 
that in both the acid Bessemer and the acid open-hearth 
furnaces we get out in quality just what we put in. While 
for some purposes phosphorus and sulphur of 0.1 per cent 
is allowable, for other purposes they should not be over 
0.025 or 0.03 per cent. To produce steel of the latter high 
quality, material containing slightly less than this of sul- 
phur and phosphorus must be charged, and these are usu- 
ally much 
higher in 
price than are 
pig iron and 
scrap contain- 
ing greater 
percent- 
ages of these 
metalloids. 
Where ma- 
terials of 2.5 
to 3 per cent 
of phosphorus 
are obtain- 

able, as, generally speaking, they are not in this country, 
the basic Bessemer should make as low phosphorus steel 
as does the basic open-hearth. 

The great advantages of the basic open-hearth process, 
then, are that for it can be utilized a much wider variety 
of raw materials than is possible with the acid open- 
hearth or either of the Bessemer processes, and, particu- 
larly that here, at least, the proper materials are readily 
available. 

The fuels used vary, of course, according to what is 
most available, considering quantity, quality, and price. 




Charging Floor of the Battery of Gas Producers Show- 
ing Rocking Arms for Gradual Feeding of the Coal 



THE OPEN-HEARTH PROCESS 157 

Natural gas has been a favorite fuel, as also has oil. But 
in many localities natural gas never was available and in 
others which were thus blessed, the supply has been ex- 
hausted. By-product coke-oven-gas and tar are being ex- 
perimented with with some success. 

Largely because of the great size of the open-hearth fur- 
nace solid fuel, such as coal which can be used for puddling 
furnaces, is not adaptable. 

As far back as 1839 attempts were made to gasify coal 
by burning it to ash and utilizing the gaseous products for 
industrial purposes. These attempts succeeded and the 
process has been brought to quite a high state of develop- 
ment. There are to-day a large number of efficient types 
of "gas producers" which furnish gas for general indus- 
trial use and it is with this "producer-gas" that a great 
deal of the steel nowadays is made. 

While endeavoring to leave out of these articles most of 
the chemistry and as much of the technical detail as is con- 
sistent with clearness, the chemistry of combustion and the 
"gas producer" is so interesting that it will be well to ex- 
plain that carbon (coal, coke, wood, etc.) can burn either 
in one or two stages. Nearly every one has noticed the 
blue flame with which coal burns in the parlor coal heater 
or in other furnaces where little draft is used and most of 
us remember that the gas which is given off from such a 
fire has asphyxiated many who were unfortunate enough 
to be sleeping in a closed room, when through insufficient 
chimney draft or a leaky stove some of the unburnt gas 
filled the room. 

This gas, which is carbon monoxide, is labeled CO in 
books on chemistry. It is the result of burning the coal 
with insufficient air. Chemically it is explained by the sec- 
ond of the chemical "equations" which follow. The third 
equation explains the second stage of the burning which 



158 NON-TECHNICAL CHATS ON IRON AND STEEL 

would occur were further air or oxygen admitted to the 
upper part of the furnace. 

The usual one-stage combustion with plenty of air: 

1. C (carbon) + 20 (oxygen) burns to C0 2 (carbon di- 
oxide). Non-poisonous. 

The two-stage combustion with insufficient air: 

2. C+0 burns to CO (carbon monoxide). Poisonous. 

3. CO+0 burns to C0 2 . Non-poisonous. 

Carbon monoxide asphyxiates by forming a chemical 
compound with the hasmoglobin of the blood, which there- 
fore is prevented from supplying the body with the oxygen 
that is required for the sustenance of life. 

Carbon dioxide is no such poisonous product, as may be 
inferred when we remember that it is the gas with which 
our carbonated waters are charged and which is so com- 
monly served with ice cream in ice cream soda. 

Now in a gas producer, by maintaining a sufficiently 
thick bed of glowing coal and admitting only such amounts 
of air as will produce mainly carbon monoxide gas, a prod- 
uct of high burning value is obtained. A kilogram (2.2 
pounds) of carbon in burning from C to CO generates only 
2450 calories or heat units, whereas its complete burning to 
C0 2 would give 8080 calories. So by conducting the carbon 
monoxide gas — the product of the first stage of the com- 
bustion — through brick-lined pipes to the furnace, and in 
the latter by addition of air allowing it to burn to C0 2 , the 
greater amount of heat (i. e., 8080 minus 2450 or 5630 cal- 
ories) is evolved in the furnace. Of course, some of this 
theoretical two-thirds which is in this way made available 
at the furnace is lost because a little C0 2 is formed, and 
always the nitrogen of the air used greatly dilutes the gas. 
But there are gains, notably the great heat which is car- 
ried over by the hot gas from the glowing bed of coal and 
that from the water-gas which is formed from steam used 



THE OPEN-HEARTH PROCESS 159 

in the producer. So, all in all, the gas generated in a "bat- 
tery" of gas producers, all of which discharge into one 
large main or header to maintain gas of average compo- 
sition, is quite a satisfactory fuel. 



CHAPTER X 
CAST IEON 

From the preceding chapters we now know pretty well 
the place which cast iron occupies in the iron family. In 
the chapters which have succeeded the one in which we 
discussed the blast furnace and pig iron, every one of the 
products except crucible steel has been produced through 
some "refining" operation which greatly changed the com- 
position, structure and properties of the product. Cast iron 
is not the result of a refining operation in this sense of the 
word. It is produced through simple mixing of pig irons 
of various compositions, usually with some admixture of 
iron castings of similar composition which have outlived 
their usefulness in the industrial world and have been re- 
turned as scrap to be remelted. 

When we say that cast iron is not produced through a 
refining operation, it must not be inferred that no change 
in composition occurs during the remelting. There is some 
change, notably a loss through oxidation from the air blast 
of a little of the silicon and manganese. Aside from this 
there usually will be absorption of enough, or sometimes 
more than enough, carbon from the coke used in melting 
to make up for the carbon which is oxidized. Usually some 
sulphur also is taken up from the fuel. There is, how- 
ever, no such actual or intended alteration of composition 
through burning out of the metalloids as is necessary for 
the production of wrought iron and steel. 

160 



CAST IRON 



161 



But from this we must not assume that the manufacture 
of cast iron for chilled rolls, car wheels, machine parts, 
valves and fittings, etc., is an easy proposition. As we 
will soon see, accurate regulation is required of metal for 
proper depths of "chill" for rolls, car wheels and cast- 
ings which must have high resistance to wear. Too, the 
metal for valves and fittings and other more or less com- 
plicated castings for 
high steam, air, am- 
monia, water, etc., 
must be uniform, of 
close grain, strong, 
yet soft enough to 
machine easily at the 
extremely high 
speeds which modern 
efficient tools and 
methods demand. 
The production of 
the best metal for 
such work requires 
the u s e of properly 
selected mate- 
rials, judicious mix- 
ing, and clever operation of the cupola furnace, that the 
molten metal delivered to the foundry for the pouring of 
the molds may be hot and fluid and of the right compo- 
sition for the particular work in hand. 

It is always interesting and instructive to follow the ma- 
terials through their course from the "raw" state to fin- 
ished products, and, therefore, we are going to take you on 
a little trip from the receiving yard of a firm making cast 
iron goods where we see the cars of pig iron just in from 
the blast furnace and where the materials are sampled and 




Sampling Cars of High Silicon Pig Iron 



162 NON-TECHNICAL CHATS ON IRON AND STEEL 



held pending analysis, to the laboratory where the sam- 
ples are analyzed, then to the storage bins where the ma- 
terials are unloaded, and, later, with the weighed charges, 
to the cupolas which convert them into molten cast iron of 
the proper composition and quality for high-grade castings. 
Twenty years ago it looked as if the iron foundry would 
be one of the last strongholds of ' i rule-of-thumb " to give 
way to scientific methods. It does not look so to-day, 
though there are many foundries which yet buy and use 

their pig iron 
on the basis of 
fracture; i.e., 
the f oundry- 
m a n guesses 
by judging of 
the color and 
closeness 
of grain and 
other charac- 
teristics of 
fresh frac- 
tures of the 
pig irons how 
suitable they are for his purpose and in what proportion 
to mix them. A skillful man can get fair results in this 
way only so long as he uses the small number of brands of 
pig iron with which he is perfectly familiar, and even then 
there must be but little fluctuation in composition of the 
irons used and he must be allowed considerable latitude 
in the quality of the iron which he produces. 

Success by this method is even more difficult now than 
it was ten years ago, for the advent of many new blast fur- 
naces and their greater variety of products have made this 
rule-of-thumb mixing a much more uncertain matter than it 




Sampling Other Pig Irons 

Pig irons of lower silicon content cannot be broken easily 
with a sledge but usually are thrown from a height across 
an ..iron block. 



CAST IRON 



163 



formerly was. Machine-made pigs, which are so generally 
on the market now, give fractures which tell little regard- 
ing their compositions. 

While some foun- 
dries still attempt to 
accomplish this 
difficult and some- 
times impossible feat, 
the majority are now 
applying more scien- 
tific methods to their 
manufacture of cast 
iron. 

Though the eye 
cannot tell surely 
from the fracture the 
composition or qual- 
ity of the iron which 
is used in making up 
the charges, chemical 
analysis does defi- 
nitely give this in- 
formation. 'There- 
fore, every car of 
pig iron purchased 




Drilling the Samples 



No oil or other lubricant is allowable and the 
drillings are taken up with a magnet that no sand 
or other impurity may get into the sample for 
analysis. 



by this firm is sam- 
pled and analyzed, 
the composition of all 
other materials used 

in its mixtures is determined, and, irrespective of fracture, 
which may or may not tell the truth regarding their compo- 
sition, the raw materials are charged with respect only to 
their actual content of the metalloids. The resulting mol- 
ten iron each day is analyzed to confirm the correctness of 



164 NON-TECHNICAL CHATS ON IRON AND STEEL 



the mixture and to furnish analysis of the "sprues" which 
next day are to be used as a part of the day's charge. 
Physical test bars, too, are cast each hour or so, and the 
tensile, transverse strengths, hardness, shrinkage, etc. are 
accurately determined in testing machines and recorded. 
In this way absolutely nothing is left to chance or to guess 

work, and, as 
you may sur- 
m i s e , any 
slight de- 
viation from 
the composi- 
tion desired is 
shown at once 
and the mix- 
ture immedi- 
ately changed 
to the extent 
necessary 
to bring the 
iron back to 
normal. It is 
surpris- 
ing within 
what narrow 
limits of vari- 
ation compositions and physical properties can be held, with 
furnace operations continually under such surveillance. 

As the basis for its cast iron, many thousands of tons of 
pig iron are each year used direct from the blast furnaces. 
The raw materials come in railroad cars or by boat. The 
inspector who represents the metallurgical department en- 
ters each car and inspects the materials, taking from each 
a representative sample for analysis. In the case of pig 




Weighing Out Portions for Analysis 

The finely divided mixed drillings are shaken from a thin- 
bladed spatula on to the balance pan. Drillings are added 
or taken off until the long needle attached to the beam of 
the balance swings over an equal number of divisions on 
each side of the center mark of the white scale in the mid- 
dle. Accuracy is 1/453,000 of an avoirdupois pound ; this 
is approximately the weight of the lead of a "pencil mark" 
one inch long. 



CAST IRON 



165 



iron this will be from four to eight half pigs, it having been 
found by experience that these represent very well the con- 
tents of the car. So each car of material is held without 
unloading until it has been determined by inspection and 
analysis that it is fully up to the specifications upon which 
the iron was purchased. 

Arriving at the laboratory, the half pigs from each car 
are drilled, equal amounts of the drillings being taken and 
mixed in an envelope which bears the name of the brand of 
iron, the number of the car, 
the date, etc. The sample 
pigs from each car are 
treated in this same way, 
each car being treated in- 
dividually. 

The envelopes containing 
the drillings then go to the 
chemists. Frequently sam- 
ples from fifteen or twenty 
cars of pig iron, with as 
many other samples of va- 
rious derivation, are being 
analyzed at the same time 

for the four or six different constituents which it is neces 
sary for the metallurgists to know and control in order that 
a highly satisfactory product may result. Though a hun- 
dred different determinations may be in progress at the 
same time, spelling "chaos" in the mind of one not entirely 
familiar with the details of the work, it will be interesting 
to single out and explain briefly how the samples are an- 
alyzed. 

In such analytical work everything is based upon weight ; 
i.e., constituents are determined and reported in percen- 
tages by weight. In chemical laboratory work everywhere 




Closer View of the Weighing 



166 NON-TECHNICAL CHATS ON IRON AND STEEL 



the metric system is used, the cumbersome English system 
of weights and measures being practically impossible. 
Thus, the metric system is the international scientific stand- 
ard. The unit taken is the gram, which is equivalent to 
1/453 part of an avoirdupois pound. One gram of pig iron 
drillings is such an amount as could be held on an ordinary 

ten-cent piece. 

Working with such 
small amounts of the 
sample, exactness 
and skill are extreme- 
ly necessary. The 
balances used are 
necessarily very deli- 
cate — just as delicate 
as were the scales 
upon which the jewel- 
er weighed your dia- 
monds — you remem- 
ber, of course. On 
these balances we can 
weigh an inc h-long 
mark made by an or- 
dinary lead pencil. 

Dissolving in Acids As the results of 

This is done under a hood that the irritating fumes f}, anaWaic lin-tro fn 
given off may be kept from the room. Lllt; ciiiciiv&ib iictvt; iv 

be known inside of 
three or four hours that the cars may be quickly unloaded 
in order to avoid demurrage, which is the penalty for hold- 
ing cars longer than the allowable time, separate portions 
of each sample are weighed out for determination of the 
silicon, manganese, sulphur, phosphorus, graphitic carbon, 
and combined carbon. These are necessary in order to de- 
termine that the iron is up to the quality specified in the 




CAST IRON 



167 



purchase contract and also to provide for its most efficient 
use in the manufacture of iron castings. 

The exactly weighed portions are put into clean, num- 
bered beakers, which are small pieces of high grade glass- 
ware that will stand sudden changes of heat and cold. Some 
of these portions are dissolved in nitric acid, some in hy- 
drochloric acid, oth- 
ers in combinations 
of acids. In each 
case the drillings go 
into solution in the 
acids, and after va- 
rious treatments of 
boiling, evaporating, 
filtering, etc., well 
known to those of the 
chemical profession, 
the desired results 
are obtained. In some 
cases it is by actually 
weighing a constitu- 
ent which has been fil- 
tered out and burned 
to ash of a constant 
known composition, 
in others it is by comparison of color with standards of 
known composition, and sometimes it is by other means. 

In all of this analytical work the chemist must take care 
to lose not one drop of the solution or one grain of the 
ash from the burned "precipitate," as the "filtered out" 
constituent is called. 

The pig iron is always bought upon guarantee that it 
will contain a certain percentage of silicon — the element 
which in cast iron is known as a "softener." But this is 




Filtering Silicons 

After evaporating the excess acid, baking dry, cool- 
ing, and redissolving in weaker acid, the silicon 
compound formed may be filtered out. The iron 
and other soluble constituents, now in solution, 
pass through the filter, which is of pure, porous, 
unglazed paper. 



168 NON-TECHNICAL CHATS ON IRON AND STEEL 




not the only thing necessary in the iron that is purchased. 
It must also show proper specified quantities of manganese, 
phosphorus and carbon, which also are very desirable ele- 
ments in iron castings, and as little of that undesirable 
element, sulphur, as possible. Therefore they pay in pro- 
portion to the content of silicon, manganese, phosphorus, 
and carbon — and penalize the seller for sulphur. 

The laboratory holds copies of the contracts upon which 
these materials were bought. If, 
upon comparison, the analysis ob- 
tained complies with the terms of 
the contract, an 0. K. unloading 
slip is made out and the receiving 
department is given directions into 
what raw-material bin in the re- 
ceiver building it shall be unloaded. 
If not fully up to the standard 
called for in the contract, the pur- 
chasing department is notified and 
the car is either rejected or ac- 
cepted upon some proper terms of 
adjustment if it can be used with- 
out detriment to the product in 
which it is to be utilized. 
Cars of coke, limestone, fluorspar, etc., are inspected, 
analyzed and treated in the same way, so that nothing is 
left to guess work. The compositions as determined by the 
laboratory serve not only as the basis for acceptance or 
rejection, but the analyses of accepted materials are for- 
warded at once to the metallurgists, who from them figure 
the mixtures to be used in the cupolas. 

Having great stocks of analyzed raw materials in the 
labeled bins in the receiver building, the metallurgists who 
supervise the mixing and melting of the iron determine by 



"Burning off" the Silicons 

The paper and contents, in a 
little crucible, are placed in a 
red-hot muffle furnace. The 
paper is such pure cellulose 
that it leaves no weighable 
ash. That which remains 
after burning is silicon oxide, 
which is a perfectly white, 
fine sand. This is very care- 
fully weighed. (Ordinary 
sand is silicon oxide usually 
slightly colored with iron.) 




X4 -+H ui q_( Q 

o o cd o+-* 



169 



170 NON-TECHNICAL CHATS ON IRON AND STEEL 



mathematical calculation just what irons and how much of 
each must be taken to give molten iron of the best compo- 
sition and properties for the castings. 

The total iron materials charged must have a definite 
amount of silicon, of manganese, of phosphorus and of car- 
bon. For a 4,000-pound charge for soft cast iron, for in- 
stance, the total sili- 
con in the materials 
which make up the 
charge must be some- 
where near 118 
pounds, the manga- 
nese and the phos- 
phorus about 30 
pounds each. The 
usual losses of these 
materials through 
oxidation are known, 
of course, and suffi- 
cient excess has been 
allowed that the 
desired final com- 
position will re- 
sult. 

On several scales 
which are regularly 
inspected and kept 
carefully adjusted, the weighers weigh out the pre- 
scribed quantities of the raw materials. "Buggies" 
holding nearly one ton each are loaded in turn with coke, 
with proper amounts of pig iron, cast iron scrap, sprues 
from the foundry castings of the preceding day, and a 
proper weight of limestone flux. Each charge of two 
tons of iron requires four buggies for its transportation 




Titrating Phosphorus 

A yellow precipitate containing the phosphorus is 
filtered out on filter paper. It is redissolved in 
alkali and titrated with a standard solution of 
nitric acid, similarly to the sulphur. The solu- 
tion in the flask turns pink with the first drop 
added after the phosphorus has been measured. 



CAST IRON 



171 



from the raw-material bins and scales to the cupolas. 
The old-time way was for laborers to dump the charges 
into the cupola and spread the materials by hand, but in 
modern foundries better ways have been provided. Here 
a charging machine operated by compressed air lifts into 
the furnace, one by 




one, the buggies of 
coke, and of the other 
materials, whence, 
after the dumping of 
their contents, the 
buggies are returned 
to the receiver build- 
ing to be filled again. 

Thus many charges 
per hour pass 
through the yawning 
charging doors of 
the cupolas, being 
dumped in fast 
enough to maintain 
the level approxi- 
mately even with the 
bottom of the charg- 
ing door. 

In starting, a wood 
fire has been made on 
the sand bottom of 
the cupola. This is covered with coke in such a way and in 
such amount that, when ready for charging of the metal, a 
column of glowing coke extends to a distance of one foot or 
two above the tuyeres. Upon this "bed" in alternating lay- 
ers are piled the weighed amounts of pig iron, sprue, scrap 
and limestone as described above. Following each charge is 



Reading the Carbons 

The higher the combined carbon the darker the 
nitric acid solution of the iron or steel. The 
solution is diluted with water or weak acid until 
the color matches that of a "known" sample or 
standard. Accurately graduated comparison tubes 
are used. 



172 NON-TECHNICAL CHATS ON IKON AND STEEL 



a layer of coke sufficient in amount to replace the "bed" 
coke which is burned away in melting the iron charge, thus 
maintaining the top of the bed of coke throughout the day 
at approximately the same height. 

Ever since 7 o'clock a. m., when the twelve to sixteen 





wmm^m 


! 


n23 


ii ■ it 
i 




pit 




■ ■ 


*^Ei 


j\ ^er/-" 




^-i*"-- ^ 


' ~~"m 






ji f ~'%m 


m,f 


| VI 




Bju.-fsaj 


^^j« 


1 m 




^ 


• ^ 


''^•"SB 


I 



Weighing the Graphitic Carbon 

The graphite is filtered out on an asbestos pad in a perforated 
platinum crucible. After drying until all moisture is gone it 
is weighed, ignited, and weighed again. The loss of weight 
equals the weight of the graphite of the sample. 

ounces of blast pressure was put on, the charges have been 
descending gradually from the charging door. Encounter- 
ing the intense heat in the "melting zone" at the top of the 
bed of coke a little above the tuyeres, the iron melts and 
trickles down through the three to five-foot bed of glowing 
coke on to the sand cupola bottom or hearth where it ac- 
cumulates. The tapper, with his iron bar and "bod stick" 



CAST IRON 



173 



with its little ball of moist fire clay, alternately opens and 
plugs the tap hole at the bottom of the furnace as occasion 
requires, but throughout the day of ten or more hours there 
is almost constantly a full stream of iron flowing from the 
spout. The big "bull ladle" which receives it, in turn gives 
it up to smaller or "shank" ladles, in which it is conveyed 
along trolleys to still smaller ladles from which it is poured 
into the sand molds to form the castings. 

As in the blast furnace, limestone is added as flux to 
make liquid and dispose of sand, dirt, scale, etc., which 
are detrimental. The liquid 
slag formed from union of 
limestone with these impur- 
ities floats upon the molten 
iron in the cupola hearth, 
as it is less than half as 
heavy as the iron itself. It 
flows almost continuously 
from a higher hole called 
the ' ' slag hole, ' ' in the rear 
of the furnace and just be- 
neath the tuyeres. The slag 
has little value except as 
material for filling pur- 
poses, etc. So-called "slag wool" can be made by blowing 
air through it. Sometimes the blast from the cupola blows 
it in such a way that this pure white "wool" is formed and 
blows out of the slag hole of the cupola. About Christmas 
time some of the workmen take quantities of it home for 
decoration and for fire-proof whiskers for "Santa Claus." 

These operations go on continuously throughout the 
day, each cupola making the particular grade of cast iron 
or "semi-steel" which is best adapted to the particu- 
lar castings to be poured, size, shape and purpose of 




Another Close-up View 




Determining Carbon by Direct Combustion 

In an electric furnace with pure oxygen passing over them, the 
drillings burn as would splinters of wood. Prom the gas 
given off the total carbon is determined with great accuracy. 



ELL ;j . ' 




W'-ff. <&$*? 


, ^— 3 1| P 


**^* 


: m^ 



Weighing Pig Iron for the Cupola 

From three to six varieties of pig iron are used 
in each charge. 

174 




The Receiver Building 

Here pig irons of different compositions are separately kept 

in numbered and labeled bins. The magnet which is used 

for unloading and handling the iron may be seen. The 
grab bucket for sand is at the right. 




Weighing the Charge of Coke 

Close weighing is necessary, for a variation of 
ten or fifteen pounds may affect the running of 
the cupola. 



175 



176 NON-TECHNICAL CHATS ON IRON AND STEEL 



CHARGING DOOR 



CHARCINC FLOOR 



the castings being the three main determining factors. 
When nearing the end of the day, charging ceases, the 
charging door is closed and the last charge, gradually de- 
scending, melts and 



flows into the bull 
ladle about an hour 
later. As soon as the 
bull ladle is emptied 
it is run out of the 
way, the cupola is 
drained of all iron 
and considerable slag 
through the tap hole, 
and the bottom doors 
of the cupola are 
dropped by pulling 
from under them the 
"props" which have 
held them in position. 
The great mass of 
bed coke follows with 
a great burst of heat, 
light and flame. This 
is quickly sub- 
dued with a stream 
of water and re- 
moved. When cool, 
the slag and accumu- 




TAPPING HOLE 



Sectional View of a Cupola 



lations are chipped from the cupola lining, burned areas are 
patched with bricks and stiff, fire-resisting mud, the bottom 
doors are raised and fastened in position, and the eight-inch 
sand bottom is packed in ready for the next day's run. After 
building a fire and getting a good "bed" of glowing coke, 
the cupola is ready again for the charging of iron. 




A Cupola in Operation 

«i he i, ^ e , a J? of iron from the cupola spout flows into a 
bull-ladle and from that into "shank-ladles." The bull- 
ladle serves as a reservoir and mixer 




Castings of Cast Iron as They Come from the 
Molds 

The "sprues" have not been removed. 



177 



CHAPTER XI 

CAST IRON (Continued) 

Unlike the modern Bessemer, open-hearth, and other steel 
products which are reworked, i.e., rolled, forged, etc., cast 
iron is a comparatively old alloy dating back over several 
centuries. It cannot be rolled, forged, or otherwise re- 
shaped, so its final form must be given to it at once by 
pouring or "casting" the molten metal into a mold. Its 
castings serve exceedingly well in the hundreds of places 
for which they are adapted. They are comparatively cheap, 
can be readily duplicated in small or large quantities, and 
those from the softer grades of cast iron may be ma- 
chined easily. 

These cast iron alloys have only from one-third to one- 
half the strength of steel or wrought iron and are, com- 
paratively speaking, very brittle. Where resistance to 
severe shock must be withstood they should not be used. 
Also, some varieties have a "habit" of growing larger 
upon repeated heating and cooling. This "permanent 
growth ' ' is particularly noticeable when the alternate heat- 
ing and cooling is at red heat or over. Pieces of cast iron 
have been made to gain 15 per cent in linear dimensions, 
and it is quite common knowledge among machinists that a 
piece of cast iron which is slightly too small can be per- 
manently expanded by heat. 

Nevertheless, the cast irons have large and legitimate 
fields in which they are very serviceable. From most of 

178 




ffi H 



o e 



D 
M O 



179 



180 NON-TECHNICAL CHATS ON IRON AND STEEL 

their important present uses they are not likely soon to be 
displaced. 

Cast irons in considerable variety of compositions and 
physical properties are available, as was indicated by alloys 
Nos. 14 to 19 which were given in the table on page 83, 
part of which is here reproduced. In alloys 3 to 13 the 
carbon exerts the great influence on the physical properties, 
and this is true also of the cast irons. But all of the latter 
have a total carbon content of more than 2y 2 per cent, 

A Few of the Cast Irons 



No. 14. White Cast Iron 

No. 15. Annealed Malleable Iron... 

No. 16. Cast Iron for Chilled Cast, ngs 

No. 17. Semi-steel 

No. 18. Gray Cast Iron 

No. 19. Soft Gray Cast Iron 



Silicon, 
Per 
Cent 



.70 

.70 

1.00 

1.75 

2.00 
2.50 



Graph- 
ite, 
Per 
Cent 



.10 
2.70 
1.00 
2.80 
3.10 
3.30 



Com- 
bined 
Carbon, 
Per 
Cent 



.65 
.05 
.00 
.40 
.30 
.15 



Total 

Carbon 

Per 

Cent 



2.75 
2.75 
3.00 
3.20 
3.40 
3.45 



Very Hard 

Machinable 

Very Hard 

Machinable 

Machinable 

Machinable 



and, under certain conditions, some of the carbon assumes 
a different form from that which we encountered in the 
steels. This modified form is "graphite," well known to 
us as a flaky, black, greasy-feeling material, which is soft 
and very fragile. Graphite in the iron alloy naturally 
weakens it and, as it is itself such a good lubricant, it 
makes cast iron machine easily if sufficient amount is 
present. 

Now, the above must be understood as being typical com- 
positions only. There are, of course, irons of all inter- 
mediate compositions, also, and while the total, graphitic 
and combined carbons, typically, are about as indicated, 
there may be wide variation. 

To illustrate what a variety of chemical and physical 



CAST IRON 



181 




No. 30. Very Soft Cast Iron. Note Large 
Graphite Flakes 



properties may be 
produced, let us as- 
sume that the total 
carbon in a certain 
cast iron is 3.25 per 
cent. If this carbon 
is all in the chemical- 
ly combined form (i. 
e., combined with the 
iron to form the very 
hard compound 
which is known to 
the metallographist 
as "cementite") the 

fracture will be white and the alloy extremely hard. If none 
of this carbon is combined, but all is in the form of graphite 
flakes throughout the 
alloy, the fracture 
will be "gray" and 
the alloy soft and ma- 
chinable. It is pos- 
sible to produce 
either of these two 
conditions or practi- 
cally any intermedi- 
ate stage ; i.e., we can 
almost at will split 
up the 3.25 per cent 
of parhou into varv- Na 31, Medium Hard Cast Iron 

u± Lciiuuii liiLU Vdi) The " C0mb i nec i car bon" is in the roundish, dark 
i-nfv noi-noTi + Qfi'flD nf parts. It is the "combined carbon" that increases 
lllg pel ceil Idgeb Ol the strength of cast iron and steel. 

graphitic and com- 
bined carbon — the total always equaling 3.25 per cent. 

The "precipitation" of graphite which is necessary for 
softness is brought about mainly through the influence of 




182 NON-TECHNICAL CHATS ON IRON AND STEEL 




No. 92d. 



Semi-Steel. A Closer Grained and 
Yet Stronger Cast Iron 



silicon, which we be- 
fore termed the 
* ' softener. " Other 
conditions being 
equal, the higher the 
silicon (if not above 4 
per cent), the higher 
will be the graphite 
and the lower the 
combined carbon ; 
and vice versa, the 
lower the silicon the 
lower will be the 
graphite and the 
higher the combined carbon. It is mainly due to the ' ' com- 
bined carbon" which is left after precipitation of the 

graphite that the al- 
loy has greater 
strength, hard- 
ness, and closer 
grain. So, just as the 
steels are stronger 
and harder as the 
carbon increases (in 
steel all the carbon 
is combined), so, 
other conditions be- 
ing equal, the 
strengths and hard- 
nesses of the cast 
irons, within usual limits, increase as the combined carbon 
increases. 

Just here it is interesting to remember that from the 
standpoint of metallography cast irons are simply steels in 




No. 33e. Mottled Cast Iron 

So-called because it. is a mixture of white and 
gray iron. 



CAST IRON 



183 



which there is what ive might call an impurity or an adulter- 
ant, graphite crystals. It will be seen at once that could 
these graphite crystals be removed from the cast irons 
shown in photomicrographs No. 74, No. 92d, No. 30 and No. 
31, we would have alloys quite similar in appearance to the 
steels shown in photomicrographs No. 3b and No. 22c which 
appeared on pages 77 and 78.* 

So the softer cast irons which are used for valves and 
fittings, machine parts, radiators, hollow-ware, etc., have 
high silicon. Parts 
that do not have to 
be machined c a n be 
of "harder" iron; i. 
e., made of iron hav- 
ing lower silicon con- 
tent. 

Manipulation 
of the silicon content 
is not the only meth- 
od by which the hard- 
ness of cast iron can 
be influenced. 
Graphite can "pre- 
cipitate" (i.e., separate throughout the casting) only if 
sufficient time is given it to do so. That is, the cooling of 
the casting after pouring must be sufficiently slow. In a 
sand mold the iron remains molten for a time, and after 
solidification it cools slowly enough that the greater por- 
tion of the carbon separates as graphite. Therefore, cast- 
ings of proper composition made in sand molds are soft 
and machinable. 

If the iron is poured into a mold the surfaces of which 
are made of iron, the molten metal upon entering becomes 

* Magnification 70 diameters. 




No. 7. White Cast Iron 



184 NON-TECHNICAL CHATS ON IRON AND STEEL 




solid almost as soon as it takes the form of the mold, and 
it cools with great rapidity. Under such conditions the 
carbon of the alloy is denied the time necessary to change 

into the graphitic form and the cast- 
ing has a white fracture and is so 
hard that it cannot be machined. 

There are many purposes for 
which the alloy should have ex- 
treme hardness and the great re- 
sistance to wear which accompanies 
such hardness. The wearing faces 
of gears, brake shoes, rolls, and 
car wheels, for instance, must be 
hard. For such products, white 
cast iron, the extremely hard con- 
Ulter Jm ! dition of the alloy, just referred to, 

is utilized. Such castings are usu- 
ally produced with a white cast iron 
face, but with a gray iron interior, 
gray iron being less brittle and less 
likely to break under shock or strain. A car wheel, for in- 
stance, has approximately an inch in depth of white iron on 
the surface which lies next to the rail on which it runs. 

Such are known 
as "chilled cast- 
ings. " Molds for 
them are usually 
made of sand, with 
pieces of iron (called 
' ' chills ' ' ) imbedded 
where white iron is 

to be produced. The molten iron next to the sand sur- 
faces cools in the usual way and is gray and soft, while 
that which lies next to the "chill" is white and extremely 



Section of Chilled Car 
Wheel 

Showing white iron rim. 




Chilled Cast Iron 

The white edge resulted from the more rapid cool- 
ing against an iron chill, as did the white rim of 
the wheel shown above. 



CAST IRON 



185 




Two-Part Molding Flasks 



hard. The "depth" of the chilled layer can be increased or 
diminished according to the thickness of the iron "chill" 
used, its temperature, and by the composition and tempera- 
ture of the molten cast iron with which the mold is poured. 

The sulphur 
and total car- 
bon of the 
molten cast 
iron also have 
consider- 
able influence 
on the depth 
of "chill." 

There is a 

cast iron alloy which is familiarly known as "semi-steel." 
It is simply a high grade and stronger "gray" iron and 
must be classed as a cast iron, as our table on page 180 
shows. While it could undoubtedly be made from materials 
which are commonly used for cast iron, it is practically 

always produced by charging 
with these a certain amount of 
steel scrap to bring about the 
lower silicon, phosphorus and 
total carbon desired. 

Because steel has a higher 
tensile strength than has cast 
iron, many have inferred that 
it was the steel addition which made semi-steel stronger 
than the ordinary soft cast iron alloy. The rather unfortu- 
nate name, "semi-steel," apparently was given because of 
the steel used and the intermediate strength which the re- 
sulting product possessed. 

However, during the melting down of the charge the steel 
scrap becomes molten and its constituents merge with those 




A Hollow Cylinder 

The casting which we are about to 
make. 



186 NON-TECHNICAL CHATS ON IRON AND STEEL 




Split Pattern op Wood, Surface-Coated 
with Shellac Varnish 



of the other iron materials charged. We get out of the 
cupola, then, a mixture which, disregarding the losses and 
gains due to the air of the blast, the fuel, etc., is an aver- 
age of the materials charged. We, therefore, no longer 
have any steel, but a cast iron which has a somewhat 

lower silicon, phosphorus 
and carbon than the softer 
cast irons. The greater 
strength of the alloy is due 
to its composition and only 
indirectly to the fact that 
steel was used in its pro- 
duction. The physical properties of the steel charged have 
been entirely obliterated in the melting process. 

This view that semi-steel only indirectly gets its increase 
in strength from the steel charged is confirmed by its struc- 
tural appearance under the microscope, as was shown in 
numbers 74 and 92d which were given on page 79, and the 
photomicrographs given here, and by its extreme brittle- 
ness under hammer blows. 
Under such shock it is but 
little more resistant than 
cast iron. 

This weakness under 
"shock" was shown by 

tests from which the table which follows was compiled. 
Bars one inch square and thirteen inches long laid on sup- 
ports exactly twelve inches apart, were struck at the center 
by a twenty-five pound weight. It took seven blows to 
break the cast iron bar, the semi-steel bar required eleven, 
while cast steel withstood ninety-two blows. Even this does 
not adequately express the great resistance of the cast steel 
(another alloy not yet discussed), for the height of the 
"drop" was being increased one inch with every blow, and 




Core That Makes Hole in Casting 




Drag, or Bottom Half op Mold, after Pattern Is Withdrawn 




Drag with Core in Place and Cope, or Top Half of Mold Ready to Close 



H ■ 

































Transparent Mold, Showing Relative Positions of Core, Casting, Sprue 

Etc. 



187 



188 NON-TECHNICAL CHATS ON IRON AND STEEL 



the cast steel bar, on account of its bending, had to be regu- 
larly turned. The total foot-pounds exerted by the blows 
are given in the table which follows : 



Alloy 


Tensile 
Strength 


Number 
of Blows 


Total Foot 
Pounds 


Cast Iron 


23,400 
35,050 
37,140 
72,120 


7 
11 
22 
92 


102 


Semi-Steel 


206 


Malleable Cast Iron (a) 


1,580 
10,112 


Cast Steel (a) 







(a) On account of bending, the malleable iron and the steel bars had to be 
turned several times. 

Semi-steel is a very close-grained alloy of ten or twelve 
thousand pounds per square inch greater strength than 
cast iron. It is a most satisfactory material for medium 
and larger sized castings for which cast iron formerly was 
used. 

Did we say that cast iron was very brittle? So it is, 

comparatively speak- 
ing. But just as the 
chemist will tell you 
that there are no sub- 
stances which are 
absolutely insoluble, 
just so does cast iron 
appear to be ex- 
tremely brittle only 
when compared with 
the iron alloys of considerably less brittleness. 

The three pictures of the hooped and twisted casting il- 
lustrate how unwise it might be to speak with absoluteness. 
A few years ago the casting illustrated on pages 190 and 
192 was brought to this country by a visitor to Europe, 
with an expression of regret that cast iron produced in this 
country did not have such qualities of elasticity as had cast 




Cast Iron Tee, Cock Plugs, and Return Bends, 
with Sprues and Gates Attached 



CAST IRON 



189 




Plugs and Wheels as They Come from the 

Mold 

Occasionally as many as 200 castings can be made 

in one mold. 



iron made abroad. 
Whereupon, without 
any change whatever 
in his iron mixture or 
cupola practice, the 
superintend- 
ent of a well-known 
foundry made cast- 
ings which were ex- 
act duplicates of that 
submitted. The three 
photographs shown 
further on (Figs. A, B, C) were of one of these castings. 
The ability to bend without breaking is, of course, largely 

due to the shape. 

As a matter of fact, 
such castings were 
not at all new in this 
country, having been 
furnished by Ameri- 
can foundries for 
electrical work for 
many years. Cast 
iron springs, piston 
rings, and many 
other articles of cast 
iron are regularly 
made, which show 
such elastic quality. 

We have said 

considerable about 

"castings." In general we know what castings are, but 

in the minds of some there may be a little un- 




Type of Molding Machine 



190 NON-TECHNICAL CHATS ON IRON AND STEEL 



certainty as to the manner in which they are pro- 
duced. 

There are few lines of human endeavor which require 

greater judg- 
ment and skill 
than does the 
making of 
molds for 
castings. 
Sound j u d g- 
ment based on 
long experi- 
ence, knowl- 
edge of con- 
ditions under 
which the 
work immedi- 
ately in hand must be done, observation, and accurate, de- 
ductive reasoning as to the causes of failure are absolutely 
necessary for success. 

In general, molding may be said to be done in "pit" or 
on the "floor" 




Another of the Many Kinds of Molding Machines 



for 1 a 


rge 


work, 


on the 


"bench" for 


smaller 


work, 


or by 


"ma- 


chine. ' ' 


Pit, 




Casting, Which Because of Its Length and Small Cross 
Sections, Requires Very Fluid Cast Iron. (Fig. A) 

floor, and 

bench molding are applicable for production of castings of 
all sizes and descriptions and this general type which we 
might term "hand molding," is the form that has been 
practiced longest. Molding machines are more or less re- 
cent inventions which have enabled certain standard shapes 



CAST IRON 191 

and sizes of castings which are in sufficient demand to be 
produced in great numbers by unskilled workmen and 
therefore at less cost than is possible by the older hand 
method. 

Each design for casting may be said to demand individual 
treatment, and the molder must select that method out of 
the many which alone, perhaps, can be successful. The 
subject is such a broad one that little will be here attempted 
further than to give by description and illustration the 
predominant points of the making of molds and castings. 
A simple, typical case of bench molding will be taken, that 
the relation of pattern, mold, core and casting may be clear. 

The molding sands used are usually natural sands which 
contain greater or lesser amounts of clay, which, when 
moist, acts as a "binder" of the grains of sand. When 
used without drying, the mold is said to be a "green sand" 
mold; if dried, a "dry" or "baked" mold, as the case may 
be. The majority are "green sand" molds. 

For the usual casting of which only a few or several du- 
plicates are wanted, the "split" pattern is generally the 
most convenient. 

The two halves of the mold, the "cope" (top) and the 
"drag" (bottom), are separately made in the two parts 
of the "flask" or molding box by "ramming" properly 
selected and "tempered" (moistened, mixed, and sieved) 
sand over the halves of the pattern. Of these, the drag is 
made first over the lower half of the separable pattern 
placed flat side down upon a bottom board. After "ram- 
ming," i.e., packing the sand, just hard enough but not 
too hard, this half mold is reversed and the top half of 
the pattern placed upon the lower half, now at the upper 
face of the drag and flat side up. A little "parting pow- 
der" or fine, dry sand is sprinkled over the fresh surface 
of the half mold so that the upper half, next to be made, 



192 NON-TECHNICAL CHATS ON IRON AND STEEL 




It Mat Be Bent Double 
Readily Without Break- 
ing. (Fig. B) 



will not stick to the lower half, but can be lifted off at the 
proper time. 

The cope half of the two-part ''flask" is now put on, 
filled and rammed with sand as was the drag. Any extra 

sand is scraped off with a straight 
edge and at the proper place a hole 
is cut with the "sprue cutter" 
straight down through the cope to 
the "parting." More commonly, 
perhaps, this "sprue" hole is made 
by withdrawing a "sprue" stick 
(of wood) about which sand had 
been packed during the making of 
the cope. It is through this hole that the molten metal will 
be poured into the mold. 

Lifting the cope or top half, it is turned upside down, 
and, after cutting in the drag the "runner" or "gate" con- 
necting the 
' ' sprue ' ' hole 
with the cast- 
ing, the halves 
of the pattern 
are carefully 
drawn that 
the sand may 
n o t be dis- 
turbed. Now 
in the cavity 

left in the drag, to make the hole in the casting, is hung 
the baked "core" of sand, held together by flour or rosin 
or a "drying" oil. The cope is carefully replaced upon the 
drag, thus "closing" the mold. 

As will be noted from the drawings, there is left be- 
tween the core and the mold a space all around, which will 




Because op Its Ability to Withstand Bending and 180- 

Degree Twists It Is Often Jocularly Referred to 

as the "Rubber Casting." (Fig. C) 



CAST IRON 193 

be filled by the metal of the casting when poured. There- 
fore the surface of the core shapes the inside, and the mold 
itself the outside and ends of the casting. 

The molten metal, entering through the vertical ' ' sprue ' ' 
hole, flows along the "runner" and into the mold through 
the more or less constricted entrance called the "gate." 
The gases formed during pouring and the air with which 
the mold was filled are driven out through the porous bodies 
of sand of the mold and core. Had the mold been rammed 
too hard the gases could not escape through the sand and 
an imperfect casting would result. 

The poured mold is allowed to stand until the metal has 
solidified and cooled sufficiently, when the casting is 
"shaken out." The sand is returned to the molder to be 
used again. The sprue and runner are broken from the 
casting, which, after cleaning by "tumbling" with others 
in a revolving mill, or otherwise, goes to the machining and 
assembling shops. 

Some form of the above general method is everywhere 
used for the production of all kinds of castings, except for 
those which can be made by machine at a lower cost for 
molds. 

This kind of molding, which we have termed "hand 
work," requires expert molders and is too slow and expen- 
sive for the hundreds of standard shapes and sizes of 
castings which are in great and constant demand. The 
latter are made on cleverly devised molding machines work- 
ing with compressed air or by hand power applied through 
a lever. The pattern is attached to the machine, set and 
very accurately adjusted by a skilled mechanic. There- 
after the sand is rammed, the runner formed and the pat- 
tern drawn by the machine itself, all of these very critical 
movements being therefore rapidly and unerringly dupli- 
catable any desired number of times by unskilled labor, 



194 NON-TECHNICAL CHATS ON IRON AND STEEL 

which has but to put on the parts of the "flasks," feed in 
the sand, set the cores, close and remove the mold, and 
begin the next. 

Sometimes there is but one, but for the smaller sizes 
there are often ten or twenty, and, occasionally, as many as 
two hundred pieces or castings in a single mold. 



CHAPTER XII 
MALLEABLE CAST IRON 

It almost goes without saying that the capacity to with- 
stand distortion without breaking was the meaning of and 
the reason for the use of the term "malleable." But 
wrought iron is malleable as also is mild steel, and, in Eu- 
rope fifty years ago (though in general not now) by the 
term "malleable iron" was meant and understood what we 
know as wrought iron. You will remember that Bessemer 's 
paper announcing his great process was entitled "The Man- 
ufacture of Malleable Iron and Steel without Fuel." The 
first reference was to wrought iron. Bessemer did not 
succeed in making this by his process but his success in the 
manufacture of steel was immense. Therefore, while in 
ordinary conversation such definiteness is not necessary, 
perhaps, and not usual here, to be safe one should say 
"malleable cast iron," and not simply "malleable iron," 
for by the latter, many Europeans still understand wrought 
iron. 

Like "Topsy" of "Uncle Tom's Cabin" fame, the vari- 
ous members of the iron family "just growed." There- 
fore a strictly logical classification and nomenclature is 
hardly to be expected. 

It was mentioned in a former article that a process for 
making malleable the brittle white cast iron was discovered, 
or at least described, by Reaumur, a Frenchman, about 
1722. It is likely that his discovery or acquaintance with 

195 



196 NON-TECHNICAL CHATS ON IRON AND STEEL 




Malleable Cast Iron Bars 



it came about through his extended experiments with ce- 
mentation steel. 

The publicity which Reaumur voluntarily gave to his re- 
searches forms a no- 
table exception to the 
customs of those days 
when it was the usual 
thing for manufac- 
turers jealously 
to guard all trade se- 
crets. These were 
handed down from 
father to son or to 
others of close inter- 
est in the business. 
So aside from Eeau- 
mur's announcements concerning malleable iron, few de- 
tails of its manufacture came to light during the eighteenth 
century. Even during the hundred years which have just 

passed there have 
been few lines in 
which greater secrecy 
has been maintained 
both in Europe and 
America. During the 
last thirty years, 
only, has real scien- 
tific work been done 
to make known the 
reactions which occur during annealing and the real causes 
of the malleability. 

The father of malleable iron in this country was Seth 
Boyden, of Newark, New Jersey, a very ingenius man who 
well deserves the monument erected in his honor by the 




Malleable Iron Castings 



MALLEABLE CAST IRON 



197 




Test Sprues, Showing White, Sliohtly Mot- 
tled, Medium Mottled, and Gray Fractures 



citizens of the city, which is pardonably proud of him. 

Boyden apparently had no knowledge of the existence 
in Europe of the malleableizing process, but after noticing 
that a piece of formerly brittle cast iron had become rather 
malleable, apparently 
through the action of 
heat, he set about 
making experiments 
to produce a malle- 
able material which 
could be produced 
more cheaply than 
wrought iron. By 

melting in a forge pieces of pig iron and then annealing in 
a small furnace in his kitchen fireplace the bars which he 
cast from the melt, he had worked out by 1826 a process 
that produced cast iron which was malleable. In 1831 he 
started a foundry and made a thousand or more different 
articles for w h i c h 
there was demand, 
and, from this begin- 
ning, an immense in- 
dustry developed in 
this country. 

"We must not forget 
that the malleable 
cast iron as produced 
in this country is an 
entirely separate and distinct thing from the European 
malleable iron, as will be shown later. So our immense in- 
dustry is our own and not a copied one. 

It is only certain members of the cast iron family that 
can be made malleable by proper heat treatment. Alloys 
No. 14 and No. 15 represent one of these alloys before and 




Test Bars with One Edge Cast against a 
"Chill" 

The composition of the mixture is regulated ac- 
cording to the depth of the chill as well as by 
appearance of test sprues. 



198 NON-TECHNICAL CHATS ON IRON AND STEEL 



after the annealing process. While No. 14 was given as a 
typical analysis for white cast iron for malleableizing it 
must be understood that compositions can vary consider- 
ably without detriment from that given. 

There is one thing, however, which is absolutely neces- 
sary and that is that all or practically all of the carbon of 
the alloy must be in the combined form previous to the 
annealing process. This means that the alloy shall be white 
cast iron and have no free graphite, for any graphite flakes 
will remain through and after the annealing process and 

weaken the alloy just 
as it weakens gray 
cast iron. 

For producing this 
white cast iron two 
processes are in gen- 
eral use — the "cu- 
pola" and the "air 
furnace." The latter 

Sketch of a Coal-Fired Air Furnace pi eClOmiliaieS. 

Operation of the 
cupola for malleable iron requires great skill and very close 
attention to detail, for, to malleableize easily and with the 
best results, the composition of the alloy must be regulated 
within narrow limits, very much narrower than for gray 
cast iron. However, this is entirely possible and cupolas 
are operated continuously for malleable cast iron for ten or 
more hours with very slight fluctuation. 

In general, operation is very similar to that described 
for cast iron except that the composition of the charge is 
necessarily different, much lower silicon being required, 
and more coke has to be used for the melting. 

Most malleable iron castings are made in sand molds, 
and, as stated, the iron poured must be of such composition 




MALLEABLE CAST IKON 



199 



and temperature that the castings so made will be white 
of fracture. It is possible to get a quick indication of the con- 
dition of the iron for pouring by making test pieces, every 
one in the same way, which, after cooling and breaking, will 
show by fracture the approximate composition of the metal. 
According to these test pieces, called "sprues," which, at 
times, may be cast as often as every five or ten minutes, 
the mixture is regulated to produce a uniform product. 

To illustrate: The fracture of a round sprue, or test 
piece, always 
7 / s inch in di- 
ameter, when 
poured in the 
san d, cooled 
there to 1 o w 
red heat, 
quenched 
in water and 
then broken, 
should be 
white with 
only a few 

flecks of dark constituent. A gray iron fracture indicates 
too high silicon content and such iron is usually termed 
"low" iron. Castings of medium or heavy section, which, 
therefore, cool slowly in the sand, if poured of too high 
silicon, i.e., "low" iron, might precipitate a little graphite 
during cooling, even though thinner-sectioned castings 
which cool so much more rapidly would come white from 
the same iron. 

While iron giving nearly white sprues is necessary 
for particularly large castings, to make sure that the 
usual run of malleable castings will come white in 
the sand requires very slightly mottled test sprues. 




Firing an Air Furnace 



200 NON-TECHNICAL CHATS ON IRON AND STEEL 



Test blocks also, with one side cast against an iron 
"chill" are poured to determine the depth of chilling, and 
test bars of various shapes are regularly made, to test 
after annealing, for tensile strength, torsion and other 
physical properties. 

"Air furnaces" are much like longer puddling furnaces. 
They vary in capacity from ten to forty-five tons while 
occasionally small ones of as little as three or five tons 

capacity are 
met with. 

The usual 
fuel is soft 
coal. The long 
flame passes 
from the grate 
at one end 
over the 
bridge wall 
and is deflect- 
ed by the roof 
down upon 
the bath be- 
neath. A chimney at the outgoing end furnishes draft. 
The furnace bed is usually of brick upon which is fritted 
(slightly fused) a mixture of sand with a little lime. In 
order to facilitate charging of the materials to be melted 
the roof is usually removable in parts, called "bungs." 
These have frame work of iron which hold in place the 
fire bricks that come in contact with the flame. During 
charging these bungs are lifted off one at a time, and the 
iron materials are dumped through the openings. Small 
doors in the sides just above the bath allow "rabbling" or 
mixing of the charge and skimming of the slag which forms, 
and one or more spouts lined with fire bricks and clay pro- 




Taking Off the Slag 



MALLEABLE CAST IRON 



201 



vide for tapping out the metal when it is ready to pour. 

Unlike puddling furnace and open-hearth no burning 
out of the silicon, manganese and carbon is desired, though, 
of course, some occurs and has to be allowed for in cal- 
culating the mixture. The intention is simply to melt to- 
gether with 
the least pos- 
sible loss a 
mixture of 
such mate- 
rials as will 
give the aver- 
age final com- 
position which 
long expe- 
rience has 
shown to give 
the proper 
qualities 
to the finished 
product. 

Charges 
usually are 

of certain percentages of pig iron with not too much phos- 
phorus, sprues from previous melts, more or less good mal- 
leable iron scrap and small amounts of steel scrap. These 
are melted down as quickly as possible. Occasionally the 
slag which accumulates is skimmed off and, after rabbling, 
test plugs are poured from the fractures of which the com- 
position of the iron is judged. 

When the silicon content is deemed proper or has been 
adjusted through longer action of the flame if too high or 
addition of more silicon in the form of a high silicon alloy 
if too low, the iron is tapped, provided it is hot enough. 




Tapping 



202 NON-TECHNICAL CHATS ON IRON AND STEEL 

Malleable iron is largely used for very small castings. 
These require very hot and fluid metal. So, even if it is 
of proper composition, the metal must be held in the fur- 
nace until it is of a high enough temperature to pour prop- 
erly. Through prolonged and strong heating the iron may 
easily become oxidized or "burnt" and much skill is neces- 
sary for proper operation of the furnace. 

After tapping, the iron must be got into the molds with 
the least possible delay. 

As has been mentioned with former processes the melt- 
ing of iron in contact with coke or coal results in more or 
less contamination with sulphur. For this reason cupola 
malleable has considerably higher sulphur than has malle- 
able cast iron made in the air furnace. Cupola and air 
furnace each has certain advantages and certain disad- 
vantages. While strength and elongation are somewhat 
greater in air furnace than in cupola malleable, both an- 
neal well and give materials which are satisfactory for 
the purposes for which they are intended. 

Cupola metal has an advantage in that the temperature 
and the composition can be closely maintained the same 
throughout the heat, perhaps more so than with the air fur- 
nace. With the latter the metal at the top of the bath is 
hotter than that underneath, and, through action of the 
flame and air, silicon is somewhat lowered before all of the 
heat can be poured, especially with air furnaces of large 
size. The metal can easily be "burnt" unless extreme 
care is taken. In the cupola we can get very hot iron con- 
tinuously so that it is unnecessary to prolong the heat with 
the danger of burning that occurs with the air furnace. 

Air furnace iron anneals rather more readily than does 
the product of the cupola, and the strength and malleabil- 
ity are usually greater. The former requires a tempera- 
ture of about 1350° F., while the latter must have 1500° F., 



MALLEABLE CAST IRON 203 

a difference of about 150° F. Whether this results alone 
from the somewhat higher sulphur of cupola malleable is 
not definitely known, but it is probable that, also, the 
slightly higher total carbon gives the iron-carbon chemical 
compound a tendency to persist more strongly. 

The open-hearth furnace is sometimes used for making 
malleable cast iron. It melts much more quickly than does 
the air furnace which requires from three and one-half to 
nine hours per heat, depending upon the size. The quality 
of the product which the open-hearth furnace produces is 
of the best, but on account of the continuous operation nec- 
essary, this type of furnace is not largely used. Malleable 
iron has also been made in the Bessemer converter, and, 
occasionally, in the crucible furnace, but in this country 
the practice is not at all common. In Germany a great deal 
of malleable iron is made in the crucible furnace. 

When dumped from the molds the castings are extremely 
brittle. The sprues are knocked off and the castings go to 
the ''tumbling" mills where they are tumbled, either with 
the sprues, with hard iron (white iron) shot or star-shaped 
pieces of iron which quickly clean the sand from them and 
give smooth, clean surfaces. 

At the chipping and sorting benches any remaining pieces 
of gates and other excrescences are removed while the cast- 
ings are being handpicked and sorted. White iron, because 
of its brittleness, breaks easily and small protruding parts 
can more readily and cheaply be removed before annealing 
than after the castings have been thereby toughened. 

Having the cleaned castings of white iron of proper com- 
position, malleability is given to them by the heat treatment 
known as "annealing." Through the influence of a cherry- 
red heat continued over a sufficiently long period the iron 
and carbon, which in the white iron are chemically com- 
bined, gradually become divorced, and, after complete an- 




204 



MALLEABLE CAST IRON 205 

nealing, the casting will be found to consist of free iron in 
which are imbedded throughout very small particles of 
coke-like carbon. Castings that before this heat treatment 
were so brittle that they broke into many pieces under a 
blow and so hard that they might scratch glass, are now 
found to be capable of withstanding considerable distortion 
without fracture and so softened that a needle may scratch 
them. 

Not only is a proper temperature necessary for best an- 
nealing, but, as stated, a sufficient time must be allowed for 
the separation of the carbon and iron. The separation re- 
quires many hours and the cooling from the annealing tem- 
perature must be slow in order that the carbon and iron 
may not again unite, as they certainly would do were the 
castings chilled in water or otherwise cooled too fast. 

Most manufacturers produce tonnage enough that cast- 
ings have to be annealed in quantity. As iron at red or 
higher heat wastes very rapidly on account of scaling (in 
fact would take fire in air if hot enough), and the quality 
of castings deteriorates somewhat if even a small amount 
of air is allowed to come in contact with them during the 
annealing process, they are generally protected by enclos- 
ing in iron containers on which tops are luted and cracks 
filled with stiff, fire-resisting mud which keeps out the air. 

These iron drums are of suitable size and shape that they 
can be stacked one upon the other to a height of from four 
to six feet. The stacks or "sets" of "saggers" as they 
are called, are run into large brick-lined retort chambers 
which are heated either with coal from a grate, by pow- 
dered coal, oil, producer gas or other fuel. The larger the 
furnace and the greater the tonnage of iron which must be 
heated, the longer will be the time necessary for bringing 
the furnace and castings up to the cherry-red heat which 
is necessary for the annealing. Therefore, the larger fur- 



206 NON-TECHNICAL CHATS ON IRON AND STEEL 




No. 109. Photomicrograph of White Cast Iron 



naces require a somewhat longer time than those of smaller 
size, though the time required for the annealing of the cast- 
ings themselves is no 
longer. In this coun- 
try with ordinary- 
sized furnaces the 
usual time for the an- 
nealing operation is 
approximately one 
week. This includes 
the heating of the 
furnace and castings 
and the cooling to a 
black neat again. 
Some manufactur- 
ers, however, anneal without pots but they aim to have the 
castings protected from the flame and air. 

Handling devices 
have been designed 
which facilitate load- 
ing and unloading 
the furnaces. With 
these the many sets 
of pots or saggers 
which the furnace 
holds can be very 
quickly charged 
or removed. 

After shaking the 
castings out of the 
cooled pots, the 
dark coating is removed from them by "tumbling" 
with iron shot, pieces of leather or other polishing 
material in tumbling mills after which they are 




No. 11.0. Photomicrograph of No. 109 after 
Several Hours of Annealing 



MALLEABLE CAST IRON 



207 




Photomicrograph of No. 
Nearly Annealed 



109 When 



ready for any machining which may be necessary. 

Photomicrographs Nos. 109, 110, 113 and 35 which show 
the samples at 75 
diameters mag- 
nification show the 
course of the anneal- 
ing process. No. 109 
was taken from an 
nnannealed casting. 
No. 110 was of the 
same iron after ap- 
proximately 
thirty hours in the 
furnace. No. 113 
shows that after 
about forty-five 
hours nearly all of the iron-carbon chemical compound has 
been broken down into black patches of free carbon, sur- 
rounded by the white 
areas of pure iron. 
After about sixty 
hours all of the iron 
and carbon have been 
divorced and the an- 
nealing operation is 
complete, as is shown 
by photomicrograph 
No. 35. 

While heat alone 
effects the divorcing 
of the carbon and 
iron, which is the es- 
sential part of the annealing process, in the greater num- 
ber of cases aid is given by what may be termed chemical 




No. 35. 



Completely Annealed Malleable Cast 
Iron 



208 NON-TECHNICAL CHATS ON IRON AND STEEL 



means. Reaumur, who about 1722 discovered the annealing 
process, used iron oxide for the purpose. The white iron 
was packed in iron ore or mill scale. At the high tempera- 
tures employed the oxygen of the ore in some way not yet 
definitely known, gradually removed the greater amount of 
the carbon from the casting. It has always been a scien- 
tific conundrum how a solid, iron oxide, surrounding an-. 

other solid, a piece of 
white iron, could re- 
move from the latter 
its carbon when 
neither of them melts 
nor mingles with the 
other. Whether some 
of the oxygen from 
the ore penetrates 
the iron and burns 
out its c a r b o n or 
whether the carbon 
of the casting itself 
migrates is not yet 
definitely set- 
tled. Certain it is 
that the carbon is 
gradually re- 
moved from the casting, from the surface first and with 
increasing length of time from greater depths. 

In European practice malleable iron castings are still 
malleableized in this way, i. e., by burning out the carbon. 
The castings are made as thin as possible and the anneal- 
ing in "packing" (iron ore or mill scale) is continued 
for from one to two weeks. At the expiration of this time 
the castings have a white, steely fracture which is entirely 
unlike the fractures of malleable iron castings which are 




No. 390b. 



Photomicrograph Showinh 
bonized Outer Layer 



Decar- 



The photomicrograph also shows that this casting 
was not fully annealed. 



MALLEABLE CAST IRON 



209 




Malleable Cast Iron in Which Practically 

All of the Carbon Has Been Removed by 

Reaumur Process Annealing 



made in this country. Photomicrographs of such malleable 
iron show few or none of the black spots which No. 35 ex- 
hibits, and analyses of castings annealed in this way give 
very low results for 
carbon. 

While in this coun- 
try the Reaumur 
process of annealing 
is not followed, a 
"packing" of ore or 
scale is generally 
used. Some use an 
inert packing such as 
sand, and as first 
mentioned, some use 
no packing at all. 
Really, one of the 
main purposes of the 

"packing" as now used is the prevention of warping of 
the castings in the pots while annealing. The annealing 
temperature is not so high as in Europe nor is the anneal- 
ing continued so long, but when 
packing is used for the shorter 
time only, some surface carbon is 
removed and the carbon through- 
out the center portions of the cast- 
ings is precipitated in the coke-like 
form which is known as "temper 
carbon" to distinguish it from 
graphite which is shown in photo- 
micrograph No. 35. To the eye, 
then, fractures of such castings show black centers and white 
rims. They are known as "black heart" castings and these 
form the bulk of the malleable cast iron made in this country. 




Fracture of Black Heart 
Iron 

Note the white rims and black 
coke-like interiors. The ma- 
jority of American malleable 
iron is of this "black heart" 
variety. 



210 NON-TECHNICAL CHATS ON IRON AND STEEL 





We may say, then, that there are in general three varie- 
ties of malleable cast iron: the "all black" which is an- 
nealed without "packing," the "black heart," annealed in 
"packing" and the most common kind in this country, and 
in Europe, but very rarely here, the "whiteheart" from 
which practically all of the carbon has been burned during 

the "anneal." 

Comparison of photo- 
micrographs No. 35 and 
No. 30 given on page 181, 
will show at once one of 
the reasons for the much 
greater malleability of 
malleable cast iron. 
While the total carbon 
present is very nearly 
the same in the two 
irons, the difference in 
physical form causes 
great difference in the 
malleability of the two. 
In the gray cast iron, 
No. 30, the carbon is 
crystalline and in the 
form of long brittle 
flakes which cut through and separate the grains of iron. 
Thus "planes of cleavage" are formed which make the 
alloy unable to resist severe shock and cause it to be any- 
thing but malleable. It is not so with annealed malleable 
cast iron. Here the carbon is in the form of small pellets 
which are imbedded among the grains of pure iron, the 
malleability of which is not seriously impaired largely be- 
cause of the continuity of the "pure iron" structure. A 
second reason for the ability of malleable cast iron to 




Malleable Cast Iron Swivels of Which 
Parts No. 2 Are Cast Tightly Around 
No. 1 and Loosened Only upon Anneal- 
ing. 



MALLEABLE CAST IRON 211 

withstand shock is that in the burning out of the carbon 
of the outer portions of the casting very small cavities are 
left. These allow the surface to become considerably de- 
formed and battered under successive shocks without great 
strain on the casting itself. 

Nothing has been said so far concerning one trait of all 
of the irons and indeed of most metals and alloys which 
are used for casting purposes. This is the tendency to 
" shrink" during the solidification and cooling of the metal 
of the casting. On account of the freezing of the outer 
portions of the casting before the metal of the inside, there 
must result certain hollow places or cavities after the in- 
side metal has cooled unless some channel is kept open 
through which fluid metal can pass inside to keep cavities 
from forming. We will not here go into the matter of 
shrinkage with its great worry to the molder nor the in- 
genuity and strategy through which he produces castings 
without shrinkage cavities. One of the methods taken to 
overcome the trouble will be explained in the chapter on 
Cast Steel which is to follow. 

There is, however, another type of shrinkage — that ex- 
hibited by the contraction of the entire piece of metal as 
it gradually cools after solidification. This presents a 
rather curious and interesting case. 

It is well known among founders and pattern makers, 
that gray cast iron shrinks during cooling about Vs inch per 
foot, white iron 14 inch per foot and cast steel 5 / 16 inch per 
foot. That is, a bar cast exactly one foot long will be found 
when cold to be y$ mcn short if of gray cast iron, % inch 
short if of white cast iron and 5 / 16 inch short if of cast 
steel. The patterns have to be made larger than the cast- 
ings desired to allow for this shrinkage. 

But, during annealing, white cast iron loses one-half of 
its 14 inch per foot shrinkage and the resulting malleable 



212 NON-TECHNICAL CHATS ON IEON AND STEEL 

cast iron is found to have a net shrinkage of but % inch 
per foot which is the same as that of gray iron. 

It appears that the precipitation of the temper carbon ex- 
pands the bar throughout to practically the same dimen- 
sions which it would have had if flake graphite had been 
allowed to precipitate through slow cooling, as is the case 
with gray cast iron. 

This is cleverly taken advantage of by manufacturers 
of swivels of malleable iron, such as those shown. The 
inner portions are separately cast first and thoroughly 
cleaned after which they are imbedded in another mold. 
The outer portions are then cast around them, shrinking 
so tightly upon the inner portions that they cannot be 
turned at all. However, upon annealing they loosen enough 
that they can readily be turned yet remain tight enough 
that they cannot be separated. 

Malleable iron from which the carbon has not been re- 
moved can be hardened and given a steely fracture by sud- 
den cooling from a red heat even if it has previously been 
annealed. Decarbonized malleable iron, also, can readily be 
recarbonized by the cementation process. These charac- 
teristics are often taken advantage of for the manufacture 
of tools from malleable iron. Hammers, wood working 
chisels, gears, etc., are quite largely made. Where they 
are sold at a cheaper price than the better steel tools and 
without misrepresentation, there can be little objection, but 
sometimes they pass for steel. 

Ofttimes malleable iron castings are made in what are 
known as " permanent molds" of iron. They are really 
"chilled castings." Annealing of these is accomplished in 
the regular way. Such castings have very smooth and 
beautiful surfaces but as the iron molds have high first cost 
they can be used only for castings for which the sales war- 
rant the expense. 



MALLEABLE CAST IRON 213 

While much less malleable than is wrought iron or mild 
steel, annealed malleable cast iron has considerable malle- 
ability. It will resist great shock and can be severely bat- 
tered and bent without breaking. It has about 75 per cent 
or more of the tensile strength of mild steel and because of 
the cheapness of its castings the malleable iron industry 
has developed wonderfully. About a million tons of this 
product are produced here each year. 

Naturally malleable iron castings are used where a ma- 
terial with properties intermediate between cast iron and 
steel will suffice. Such are castings for railroad cars, for 
reapers, binders, and other agricultural machines, pipe fit- 
tings, and the cheaper grades of tools. 



CHAPTER XIII 
CAST STEEL 

We have seen how primitive man hunted and fought with 
no implements and weapons better than clubs, bows and 
arrows, and stone hatchets, and how his wife cracked and 
ground the corn between flat rocks or in mortars of stone. 
In the succeeding ' ' Bronze Age ' ' we found ornaments, idols 
and tools being made of copper or the copper alloy, bronze. 
It was only after the next great advance that we found man 
utilizing iron for his purposes of civilization. This metal, 
which with us is so common, was in those days very expen- 
sive, so much so that it could be used only for purposes of 
war and as the gifts of kings. 

But the world was traveling fast and it was not long be- 
fore the iron-carbon alloy, steel, was produced. Even so, 
many hundreds of years elapsed before the present wonder- 
ful age was ushered in through the great inventions of 
Henry Bessemer and the Siemens brothers. And while fine 
steels for swords and tools have had an incalculably great 
influence upon the development of the human race, it was 
the mammoth production of Bessemer and open-hearth 
steel which permitted its general use as a material for con- 
struction of ships, bridges, buildings, and for railroads, 
that made this the "Age of Steel." 

Speaking in terms of the power house, it is also the 
"Age of Cast Steel." Twenty-five years ago the manu- 
facturer and power house man were quite content with 

214 



CAST STEEL 



215 



their " saturated" steam temperatures and pressures. With 
cast iron valves and fittings their plants were well equipped. 

But the world did not stand still. It became known that 
by heating the steam out of contact with the water in the 
boiler it lost the moisture which it carried and became dry 
and then could be charged with as much additional heat as 
it was desired to give to it. This "superheated" steam, 
of course, would do more work and it had also certain other 
advantages 
which the old- 
fashioned 
"saturated" 
steam had 
not. 

But while 
cast iron fit- 
tings gave 
satisfac- 
tory service 
up to temper- 
atures, say, 
around 450° 
F., t h e y fal- 
tered when 

forced to work under the new conditions which meant de- 
cidedly higher temperatures and pressures. And, too, the 
repeated heatings and coolings which were often necessary, 
disclosed a disadvantage previously unknown — a so-called 
"permanent growth" of the cast iron which was attended 
by loss of strength, and altogether it was soon found out 
that when superheated steam was to be used, higher types 
of materials were advisable than those which had been 
used under old conditions. 

Superheated steam has rapidly come into general use. 




Steel Castings Showing the Risers on the Flanges 

Castings for use on steam, ammonia, water lines, etc.. must 
be of very close-grained metal and require much larger 
risers than castings for less exacting service. 




216 



CAST STEEL 217 

Some of the new locomotives and most of the modern power 
plants are now built for as much as 200° superheat, i.e., a 
total temperature of approximately 600° Fahrenheit. 

Valves and fittings of cast steel not only are the articles 
"de luxe" for such service but they have come to be con- 
sidered the necessary articles and their advantages have 
only fairly begun to be appreciated. 

Though our most august scientific societies are proposing 
and debating upon systems of classification which shall in- 
clude and satisfactorily define all of our ferrous metals, a 
satisfactory one has not yet been evolved, and, considering 
the intricacy of our ferrous metallurgy and the discoveries 
which are being made almost daily, the outlook for a strictly 
logical classification is not yet flattering. 

With "Cast Steel" our metallurgical nomenclature is 
again faulty. Before what we now call the "steel casting" 
was known, crucible steel was poured into ingots, "forged" 
into tools just as it now is and often went under the name 
"Cast Steel" to distinguish it from the contemporaneous 
material, wrought iron. So to-day we buy many tools and 
implements which bear the name cast steel, which we 
know to have been forged in bringing them into their final 
shape. 

But it is not these which we mean by the term, cast steel, 
but rather those steel products which get their final form 
by being "cast" from a fluid condition into a mold. These 
are what are rapidly coming to be understood when the 
term "cast steel" is used. 

Satisfactory metal for steel castings may be made in any 
of three or four types of furnaces, but, as was suggested 
before, the making of molds for castings is a fine art, as is 
the preparation of the metal which is to go into them. Fur- 
ther, the making of that special class of castings which are 
to withstand water, steam or air pressure is a very differ- 



218 NON-TECHNICAL CHATS ON IRON AND STEEL 



ent thing from the making of steel castings for other pur- 
poses, and this is too often forgotten. 

For the former are necessary particularly close-grained 
castings, free from flaws or spongy spots. Under the 
great pressures applied such defects would certainly allow 
leakage. 

Whatever the method of production of steel for castings 
the metal is poured into molds to receive its final shape. 

Because of the 
intensely high 
heat of the 
steel only 
sands of great 
refracto- 
riness (resist- 
ance to heat) 
can be used as 
material for 
the mold. 
White silica 
sand is such a 
material and 
is generally 
used, mixed with enough clay and molasses-water to give 
it "bond." While molds for some steel castings are made 
in "green" (i.e., unclried or unbaked) sand, baked molds 
are preferred for fine finish and surest results. After the 
making of the molds in the usual way they are sprayed with 
very finely powdered white sand or quartz mixed with a 
little molasses-water. They are then thoroughly dried in 
an oven. 

Cast steel shrinks during cooling even more than malle- 
able iron and the pattern and mold must be made to allow 
for this. Upon the freezing of the surfaces of the casting 




Flanges and Fittings op Cast Steel 



CAST STEEL 



219 



with consequent attainment of rigidity, the interiors, which 
freeze last, may have cavities unless means for avoiding 
them is provided. For this purpose heavier pieces, which 
later can be cut off, are cast upon such parts of the casting 
as tend to have "shrink holes." These may be likened to 
receptacles filled with fluid metal, which being larger than 
the parts of the castings which they "feed," hold excess 








Grain of Steel Castings as They Grain op Steel Castings after 

Come from the Mold Annealing 

(Magnification 60 diameters) 

metal in fluid condition until the casting itself has become 
solid throughout. Such are usually called "risers" or, in 
Europe, "lost heads," and the molten metal in them flows 
down into the interior of the casting and fills the shrink 
holes which are forming. Not only must the risers be large 
enough that the metal in them is the last to solidify but 
they must be built high enough above the casting that suffi- 
cient pressure is exerted on the steel entering the shrinking 
parts to make its entry sure. 

Baked molds, of course, are comparatively rigid. As the 
risers which stand on top of the flanges and other high 
parts of castings aid in resisting the natural shortening 
of long castings during and after "setting" of the metal, 



220 NON-TECHNICAL CHATS ON IRON AND STEEL 



there is great liability that the still red-hot casting will 
crack somewhere along its length. It is therefore neces- 
sary to loosen with bars the sand of the mold as soon as 
the metal of the casting has set, particularly between the 
risers, and to break out the sand of the core inside, around 
which the shrinking metal might crack were the sand left 
in its hard packed condition. 

After the casting is shaken out from the mold, it is 
cleaned and the risers cut off either by sawing or with the 

more modern 
oxy-a c e t y - 
lene torch 
flame. 

Steel cast- 
ings should be 
annealed 
in order to 
"refine," i.e., 
make finer 
the grain of 
metal a n d to 
equalize 
"strains" which are set up in the castings during cooling. 
Coarse grain and internal strains tend to make the cast- 
ings brittle. No such extended annealing, however, is nec- 
essary as is the case with malleable cast iron, for no divorc- 
ing of carbon from the iron with separation of free car- 
bon is possible. The castings are carefully heated to a tem- 
perature of about 1600° or 1700° Fahrenheit and allowed 
to cool slowly. 

After annealing, they are cleaned and excrescences re- 
moved by chipping, after which the castings are tapped, 
drilled or otherwise machined according to the purposes 
for which they are intended. 




Other Typical Steel Castings 




221 



222 NON-TECHNICAL CHATS ON IRON AND STEEL 



While more costly in manufacture and installation than 
are those of cast iron, valves, fittings and other cast steel 

products are, so far 
as we now know, 
practically perma- 
nent. Their notable 
shock resisting qual- 
ity is well shown in 
the following table 
which is reprinted 
from page 188. 

It is to be noted 
that while malleable 
cast iron far sur- 
passes ' ' semi-steel ' ' 
in this property, 
though their tensile 
strengths are ordi- 
narily somewhere 
near the same, cast steel, in turn, offers more than six times 
the resistance of the malleable iron to shock and has nearly 
double its tensile strength. It is this great strength and 




Pouring Steel into Molds from a Bottom-pour 
Ladle 



Alloy 


Tensile 
Strength 


Number 
of Blows 


Total Foot 
Pounds 


Cast Iron 


23,400 
35,050 
37.140 
72,120 


7 
11 
22 
92 


102 


Semi-steel 


206 


Malleable Cast Iron 


1,580 


Cast Steel 


10,112 







resistance to shock, heat and pressure, with freedom from 
"permanent growth" under alternate heatings and coolings 
that make cast steel such a valuable material for the many 
purposes for which castings are to-day employed. Millions 
of steel castings annually find varied application. 



CAST STEEL 



223 



In modern power houses and other commercial steam 
and hydraulic installations particularly, steel castings have 
come to be the materials usually specified and approxi- 
mately the only ones which satisfactorily serve under the 
severe conditions of to-day. 

Undoubtedly the first steel castings were poured from 
crucible steel, though we must remember that the crucible is 
a melting and 
not a refining 
furnace. This 
was only nat- 
ural. In the 
crucible the 
metal c a n be 
made very hot 
and fluid, and 
if of proper 
composi- 
tion and 
properly 
"killed" cru- 
cible steel 
makes very 
fine castings. 
Crucible 

steel castings, however, are not in as fortunate a position as 
are other products of this high grade material. Tool steels 
ordinarily bring high enough price that there remains a 
profit to the manufacturer though his manufacturing cost 
is necessarily high. In the steel casting line, however, there 
is much keener competition and crucible steel has had con- 
siderable difficulty in maintaining its place. It seems to be 
a matter of price alone. 

Open-hearth steel is very largely used for steel castings, 




Pouring from a Lip-pour Ladle 



224 NON-TECHNICAL CHATS ON IRON AND STEEL 



more than two-thirds of all made in this country being of 
this material. About one half of these are poured from 
basic open-hearth metal, and the other half from acid metal. 
It is generally considered that the product of the acid- 
lined furnace is a little freer from over-oxidation. 

Open-hearth steel cannot generally be as hot and fluid 
as are the steels made in other types of furnaces. For 

this reason as 
well as be- 
cause of the 
larger size of 
the usual 
open -hearth 
furnace, small 
castings are 
not generally 
poured from 
this steel. It 
is for steel 
c a s tings of 
considerable 
size and where 
there are suf- 
ficient orders to warrant a steady and large output that the 
open-hearth has its place. True, smaller open-hearths are 
now built, some of them of only two or three tons capacity, 
but, in general, the standard open-hearth for steel castings 
is of fifteen tons or more capacity and of the style of the 
open-hearth furnaces which were described in Chapter IX. 
In their proper sphere they are highly satisfactory, but 
they are "inelastic" in that they must be run continuously 
day and night and should not be allowed to cool until ex- 
tensive repairs are imperative. 
It was mentioned that in the open-hearth process the 




Tapping Side op Two-ton Oil-burning Open-hearth 
Furnace for Steel Castings 



CAST STEEL 



225 



furnace is always hotter than the metal which it contains 
and that the heat which can be put into the steel is limited 
by the ability of the refractories of which the roof and side 
walls are made to withstand melting. In the Bessemer 
process the metal is hotter than the furnace because the 
heat is generated by combustion of certain of the metal- 
loids contained in the metal itself. As metal for castings 
must be very hot and fluid the Bessemer process is very 
satisfactory for the 
making of steel for 
castings. 

It has, also, the ad- 
vantage of "elastic- 
ity." The supply of 
metal is practically 
continuous and one 
furnace can make 
from one to eighteen 
or even more heats 
on day turn only and 
be shut down for the 
night turn or longer 

° o • A 30-ton Basic Open-Hearth Furnace Tapping 

and then Started The overflow from the ladle into the pit is slag. 

again without such 

loss as would result from the shutting down of an open- 
hearth furnace with regenerators. 

For the making of metal for steel castings, very small-, 
sized Bessemer converters are used which make from one 
to three tons of metal per blow. Some converters of as 
little as one-half ton capacity are being used. While some 
are of the "bottom-blown" type already described, the 
majority are what are called "surface-blown" or "side- 
blown." In these, from four to eight round tuyeres, about 
one and one-half inches in diameter each, pierce the brick 




226 NON-TECHNICAL CHATS ON IRON AND STEEL 



or ganister lining just above the surface of the bath. They 
slope downward a little toward the bath so that when the 
converter is tipped to its upright or blowing position the 
air blast will strike the adjacent edge of the metal and blow, 
across its surface. This three or four pounds per square 

inch of air blast 
keeps the metal in 
circulation, mean- 
while burning out 
its silicon, manga- 
nese, and carbon, just 
as it does in the 
larger bottom-blown 
converters. Surface- 
blown give hotter 
metal than do bot- 
t o m-b 1 o w n con- 
verters and very fine 
steel castings are 
made from their 
metal. For these con- 
verters, which are 
practically all acid- 
lined (i.e., with silica 
or clay brick or gan- 
ister), metal 1 o w in 
phosphorus and sul- 
phur is regularly drawn from a cupola specially run for 
the purpose. 

The remaining recognized type of furnace for steel for 
castings is the comparatively new electric furnace. 

Commercial melting of metals by the electric current 
has been sought for half a century. In 1879 the first fur- 
naces of promise were patented by Sir William Siemens, 




Small Side-Blown Converter Making Steel for 
Castings 



CAST STEEL 



227 



BRICK LINING 



STEEL SHELL 



WIND.B 



one of the Siemens brothers who became so well known 
through their great work with the open-hearth furnace, the 
gas producer and many other things metallurgical. While 
Siemens melted as much as twenty-two pounds of iron per 
hour in his furnace, the cost of the electric current at that 
time was so high as to be practically prohibitive for the 
manufacture of steel in competition with the open-hearth, 
Bessemer and cruci- 
ble processes. 

Little of great mo- 
ment in the electric 
furnace line devel- 
oped during the nine- 
teen years which fol- 
lowed. Then, in 1898, 
Stassano in Rome, 
Italy, constructed a 
furnace in which 
three carbons gave 
an electric arc above 
the surface of the 
bath. About the 
same time Heroult a drawing of side-blown converter in blowing 

' Position, Showing Edge of Metal Even 

Frenchman, was de- with row of tuyeres 

veloping the electric 

furnace which to-day has become so well known in this 
country, and which bears his name. Other well known 
furnaces of the arc type are the Gronwall-Dixon, the Sny- 
der, the Girod and the Rennerfelt. 

In general, electric furnaces have more or less round 
steel shells with shallow brick, magnesite or sand-lined 
hearths, and sidewalls and removable roofs of brick. Heat, 
of course, is furnished electrically. In most of them long 
carbon electrodes are lowered through holes in the roof 



TUYERES 




228 NON-TECHNICAL CHATS ON IRON AND STEEL 




A Gronwall-Dixon 5-Ton Electric Furnace 
Tapping 



until the lower ends strike an arc with the metal on the 
hearth. The number of carbons may be from one to four 
or more depending upon the style and size of the furnace 

and the manner in 
which electrical con- 
nections are made. 
All of the furnaces 
mentioned have been 
used for the produc- 
tion of steel for cast- 
ings and the Heroult 
and Girod are in use 
in larger sizes for 
electric steel for rails 
and miscellaneous 
products. The steel 
is first cast into ingot 
molds and is later rolled down into bars, rods, etc. 

All of the above use carbon electrodes and are known as 
"arc" furnaces. 
There is a distinctly 
different type of fur- 
nace which, also, 
is in use in com- 
mercial sizes. This 
is the "induction" 
furnace. In this, 
what is known to 
electricians as a sec- 
ondary current is "induced" in the bath itself and 
heats the metal. Of this type the Kjellin and the 
Rochling-Rodenhauser are the best known in this coun- 
try. While they are in use in the larger sizes for produc- 
tion of steel for ingots, these two furnaces do not seem to 





First Experimental Arc Electric Furnaces 
Patented by Sir William Siemens in 1879 



CAST STEEL 



229 




Drawing of the Snyder 
Electric Furnace 



have been used to any extent for metal for steel cast- 
ings. 

The details of construction of the furnaces which are 
used for metal for castings are 
more or less different, but they are 
not of particular interest to us. 
The working of all is similar and 
a general description should suf- 
fice. 

Whether starting with furnace 
cold or hot, materials in molten or 
in the more usual "cold" form are 
charged on the shallow hearth of 
the furnace. The charging doors 
are closed, the current is turned on and the carbon elec- 
trodes are lowered until an arc is struck between the upper 

electrodes and the 
metal on the hearth, 
which in some way is 
made to connect with 
the negative elec- 
trodes. In one or two 
of the types men- 
tioned the arc plays 
between the carbons, 
all of which are above 
he bath. 

At first there are 
great fluctuations in 
the current intensity 
because of the un- 
even surface presented by scrap steel on the hearth. In 
a short time, however, the current steadies. The intense 
heat of the arcs soon brings cold steel to a molten condition. 




Small Snyder Electric Furnace Tappini 



230 NON-TECHNICAL CHATS ON IRON AND STEEL 



ELECTRODES 



Occasional attention from the attendant is necessary to 
see that the melting is even and that any outlying pieces 
of steel are pushed to the center where they must melt. 
In the basic-lined furnaces lime is usually charged with 

the cold steel. With 
the iron oxide which 
is added from time to 
time this forms a 
highly oxidizing slag, 
which, after it takes 
the phosphorus from 
the metal, is skimmed 
off. 

As you will remem- 
ber, the other proc- 
esses stop at this 
point, little further 
refining being pos- 
sible. In the electric 
furnace, however, the 
sulphur, also, can be 
reduced to almost 
any desired amount 
by use of a further 
addition of lime, and 
greater heat. Not 
only can the sulphur 
be reduced to very small percentages but the over-oxidized 
bath can be brought to neutral condition and the green or 
black slag made white with return of its manganese and 
iron to the bath. This is accomplished by addition of small 
amounts of powdered coke or coal. The whole process is 
under very accurate control. 

With a practically white slag, which is the signal that 




Sketch of the Heroult Three-Phase Electric 
Furnace 

There are three electrodes, all of them above the 
bath. Only two show here. 



CAST STEEL 



231 



the deoxidation of the bath is complete, and the sulphur re- 
duced, the steel is ready to pour provided it is hot enough. 
Tests of this are usually made either by pouring a little 
of the steel from a small ladle and observing its fluidity 
or by observing the quickness with which the end of an iron 
bar is melted off when plunged into the metal in the furnace. 

Of all the met- 
allurgical steel 
furnaces, the 
electric furnace 
is the most sus- 
ceptible of ac- 
curate control. 
With the heat 
applied direct- 
ly to the metal 
in the cleanest 
way possible, i. 
e., without the 
admission 
of coal ash or 
gas or air of 
the blast, the 
atmosphere in 
the tightly 
closed electric furnace can be made "oxidizing," "neutral" 
or "reducing" at will. The metal can be held in the fur- 
nace and additions made, samples taken, and the operations 
conducted with regulation and certainty. 

This newly devised metallurgical apparatus is coming 
to be largely used in the production of tool steels. While 
it has not displaced the crucible method for the production 
of steels of the very highest qualities, it has proceeded far 
enough in this direction in the very limited number of years 




The Hekoult Electric Furnace 



232 NON-TECHNICAL CHATS ON IRON AND STEEL 

since its introduction, that it is certain that the crncible, 
even for tool steels, is to have a keen competitor. Tool 
steels in considerable variety are to-day being quite satis- 
factorily made in the electric furnace and it is not at all un- 
likely that steels of the very highest grade will shortly be 
produced by this method. 



CHAPTER XIV 
THE ALLOY STEELS 

We have learned that steel, fundamentally, is an alloy of 
iron with carbon, i.e., carbon is the characteristic element. 
We are now to note what often seem to be exceptions to 
this rule. While in reality steel is just this iron-carbon 
alloy, there are alloys known as steels to which such strong- 
characteristics are given by elements other than carbon, 
that carbon seems not to be the defining constituent at all. 
Indeed, in some of these, the carbon content may be small 
enough that, judging from our experience with the carbon 
steel series, we would not expect any such physical prop- 
erties as some of these alloy steels show. 

You remember that in olden days they distinguished 
between wrought iron and steel by quenching the piece in 
water from a cherry-red heat. If the piece was hardened 
and made brittle, by this treatment, it was thereby proved 
to be "steel." Also, it is generally known that by anneal- 
ing a piece of hardened steel, which usually means holding 
at a cherry-red heat for a time and then cooling slowly, it 
is made soft. 

Then what shall we say concerning a certain one of these 
new alloys, Hadfield's manganese steel, which is made very 
much less brittle and a little softer by quenching, but which 
refuses absolutely to soften under annealing treatment — 
in other words, is almost the opposite of what we know 
as steel in these chief defining traits? The nickel steel 

233 



234 NON-TECHNICAL CHATS ON IRON AND STEEL 

which contains 15 per cent of nickel, also, exhibits just 
these characteristics, being softened by quenching but not 
by annealing. 

Again, while iron, the carbon steels, and even the mag- 
netic oxide of iron which contains only about 72 per cent 
of the metal, are strongly magnetic, manganese steel which 
has 85 per cent of iron is so non-magnetic that it is some- 
times used in place of brass or bronze where an entirely 
non-magnetic material is required. The nickel steels with 
24 per cent or more of nickel are also non-magnetic though 
both constituent metals, alone, are strongly attracted by the 
magnet. 

These are some of the things which make a logical classi- 
fication of the iron family so difficult. Though derived 
from the steels which we knew and made from the same 
materials with the exception that a greater amount of one 
constituent, manganese, is added, or perhaps, in other cases, 
another element or two, the resulting alloys have markedly 
different and often contradictory properties. 

However, we must not be led astray. In all probability 
carbon is still the necessary constituent, but much less of it 
is needed to produce results when the other elements are 
present. There is no doubt, however, that in "manganese 
steel" or in "nickel," "chrome," "tungsten," "silicon," 
"vanadium," titanium," and other alloy steels, the added 
element or elements exert very strong modifying influences, 
and sometimes obscure the influence of the carbon. 

In the first place, we better at once dispose of certain of 
these steels by terming the added element a "scavenger" 
only. Such usually are "titanium" and "aluminum" 
steels. These are generally ordinary carbon steels in which 
a very small amount of titanium or aluminum has been 
used to rid the alloy of certain gaseous or other deleterious 
elements. Upon analysis, steels so treated often show no 



THE ALLOY STEELS 235 

trace of the element which has been added to do the work, 
all of it having passed into the slag, carrying with it the 
obnoxious substances, which, had they remained would have 
injured the quality of the steel. Manganese and silicon 
which were spoken of in the discussion of the Bessemer 
process as deoxidizing the metal, also exert just this same 
influence, though there is usually added of these enough that 
a certain percentage remains in the finished steel. Vana- 
dium and titanium have a particular affinity for oxygen and 
nitrogen, and aluminum for oxygen. By chemically com- 
bining with these gases in the metal, and through possible 
other influence, they help to produce sound steel having 
very good physical properties. Vanadium, however, is 
much more than a "scavenger" as will be seen later on. 

Manganese Steel 

Manganese steel was discovered and highly developed by 
Robert Hadfield of Sheffield, England, along about 1882. 
His 11 per cent to 14 per cent manganese steel with about 
1 per cent of carbon has such great hardness that it cannot 
be drilled or cut with tools. In forgings and castings it is 
used for milling machinery for ore treatment ; manganese 
steel rails inserted around sharp curves and for "frogs," 
etc., under severe service conditions outlast ordinary steel 
rails three or four times; it goes into various rolls and 
crusher parts, steam and dredge shovels, grab-buckets, sand 
pumps, gears, pinions, etc., which have to resist heavy wear. 
It is much used, too, as a material for burglar-proof safes. 
The alloy is far too hard to drill and too tough and strong 
to be broken. It is said that no manganese steel safe has 
ever been drilled or forcibly entered. 

In forming irregular shapes, manganese steel must be 
cast and finished by grinding but for ordinary bars and 
rails it can be rolled. In the "raw" condition it is quite 



236 NON-TECHNICAL CHATS ON IRON AND STEEL 

brittle and extremely hard. Quenching from a cherry-red 
heat greatly toughens it and makes it ductile. Though now 
it can be dented by a hammer blow and marked with a file, 
it always is so tough that it cannot be machined with any 
tool. Ordinary annealing treatment has no softening effect 
on the alloy. 

Silicon Steels 

When alloyed in the steel in certain quantities, silicon 
gives desirable properties. Steels with from one to two 
per cent of silicon in the tempered condition are very tough. 
For this reason the leaves of automobile springs are often 
made from it. Steels with from 3 to 5 per cent of silicon 
are much used in electrical appliances because of their 
improved magnetic properties. 

Molybdenum Steels 

To a certain extent steels containing 3 or 4 per cent of the 
metal molybdenum, and 1 or iy 2 per cent of carbon are used 
in the construction of permanent magnets. ; It is said that 
molybdenum is used in some modern guns, which longer 
resist the corrosive effect of the powder-gases because of it. 
A certain amount goes into the high-speed steels where it 
replaces part or all of the tungsten. Here, however, it has 
been a disappointment and the amount so used seems to be 
decreasing rather than increasing. 

Tungsten Steels 

Steels with about x /2 P er cent of each of carbon and 
tungsten are occasionally used for manufacture of springs, 
and with greater amounts, e.g., % per cent of carbon and 
5 or 7 per cent of tungsten, for permanent magnets for 
which they are claimed to be the best material known. The 



THE ALLOY STEELS 237 

use of tungsten in the tool steels (other than the high-speed 
steels) is considerable. 

Nickel Steel 

Nickel steel is much used on account of its high strength. 
The most usual alloy, perhaps, is the one which contains 
about 3y 2 per cent of nickel. This is in addition to the 
carbon which may vary between .15 per cent and y 2 per cent. 
This 314 per cent of nickel adds several thousand pounds 
per square inch in strength to the steel, and when tempered, 
both the strength and toughness are greatly improved. 

Nickel steels of these compositions can readily be forged 
and rolled. They are used for drop forgings, machine 
parts, engine and automobile parts, in seamless tubes and 
for bridge members of great span. 

Nickel will not rust so it does not surprise one that with 
22 per cent or more of nickel the steel is almost immune 
from ordinary corrosion. Steels containing from 25 to 46 
per cent nickel are variously used for resistance wire, for 
valve stems, valves for motors, etc. The 36 per cent nickel 
steel is the alloy, "Invar," which has such slight expansion 
and contraction with heat and cold that it is used for clock 
pendulums, watch parts and for parts of measuring instru- 
ments. 

Forty-six per cent nickel steel is called "Platinite." It 
has practically the same rates of expansion and contraction 
with heat and cold as glass and for this reason it finds 
extensive use in incandescent electric lamps. Wires of 
the alloy are fused into the glass bases and connect with 
the filaments in place of the expensive platinum which for- 
merly was used. 

As remarked above, the 13 per cent to 15 per cent nickel- 
iron alloys soften with quenching but not with annealing. 
The 15 per cent nickel steel has the highest strength of the 



238 NON-TECHNICAL CHATS ON IRON AND STEEL 

nickel-iron-carbon series. Though nickel and iron are each 
strongly magnetic, alloys of the two which contain 24 per 
cent or more of nickel are not magnetic. 

Chrome and Nickel-Chrome Steels 

While ''simple" chrome steel is pretty well known as a 
material for products which require great hardness, such as 
balls, roller bearings, files, rolls, five-ply safes, stamp shoes, 
projectiles, etc., and heat-treated chrome-vanadium steels 
are now extensively used in forged frames and shafts of 
automobile and other machines, a combination of nickel and 
chromium gives steels which have been great favorites. 
With 2 to 3y 2 per cent of nickel, not over 3 per cent of 
chromium and y 2 per cent of carbon, these steels, when 
expertly heat-treated, can give "elastic limits" anywhere 
between 40,000 and 250,000 pounds per square inch, with 
good freedom from brittleness. They are very largely used 
for automobile gears, axles, and other parts, for armor 
plate, for projectiles and for many other purposes. 

These alloys are also used for castings. 

Chrome-Vanadium Steels 

Within a comparatively short time the chrome-vanadium 
steels have come to be very largely used, often in place of 
the chrome and nickel-chrome steels. As vanadium is a 
"deoxidizer," whereas nickel is not, the chrome-vanadium 
steels show fewer imperfections than the nickel-chrome 
steels and they also roll, forge and machine better. 

They are used for automobile frames, shafts, for miscel- 
laneous forged and rolled articles and for heat-treated 
armor plates. Of this comparatively new material about 
90,000 tons were made during 1913, according to a recently 
issued bulletin of the Department of the Interior. 

It is impossible, of course, to even begin to impart any 



THE ALLOY STEELS 239 

adequate conception of the qualities and great importance 
of the alloy steels for purposes of construction. As has 
been shown they are special steels for special purposes and 
their application is wide. Incorporation of the new element 
in the alloy imparts peculiar and valuable properties : for 
example, 12 per cent of manganese, great hardness and 
toughness; 23 per cent of nickel, non-corrosive properties 
and great strength; chromium, nickel with chromium or 
chromium with vanadium, strength and high elastic limit 
(resistance to distortion) as well as great hardening power 
when desired, this, of course, the usual hardening through 
quenching from a cherry-red heat. 

Very often instead of the single denning element, a com- 
bination of two, three or even four of them is used. Such, 
of course, are rather complicated steels having combina- 
tions of properties as might naturally be expected, though 
very often these resulting properties are not those which 
are expected. In fact no one can tell in advance what 
properties any new combination of metals in an alloy will 
produce and often new proportions of the same constituent 
metals give entirely different and unique results. 

The only certain method of ascertaining what character- 
istics and properties a new alloy will have is to develop it 
and in that way find out. 

Description of a special and extremely important class 
of these alloys, the "high-speed steels," will serve to show 
how laborious, slow and expensive a process development 
of new alloys may be and what unlooked-for results are 
sometimes obtained. 



CHAPTER XV 
THE HIGH-SPEED STEELS 

During early centuries the art of metal cutting made little 
progress except in-so-far as the application of greater driv- 
ing power and the use of better machines were concerned. 
Lathes had been known since the sixth century B. C, at 
least, but, of course, little was or could be accomplished, 
comparatively speaking, before the invention of the steam 
engine by Watt, which was the first contrivance to give 
sufficient power for machining purposes. During the cen- 
tury which followed Huntsman's time, steel makers and 
smiths became very expert in the manufacture and temper- 
ing of carbon steels. Lathe tools were made of these carbon 
steels, the only available material, but even with the better 
machine shop practice of the 19th century they were ca- 
pable only of what we now consider to be inefficient results. 
The trouble was that since carbon tool steel gets its hard- 
ness from quenching from a red heat and then "drawing" 
the temper by reheating and slowly cooling from 400° or 
500° F., tools made from it could not retain their hardness 
if their cutting points became much heated, as occurred if 
the lathe was run too fast. The usual cutting speed, there- 
fore, was 20 or 30 linear feet per minute. Speeds in excess 
of this took the temper out of the tools and soon made them 
useless. 

About 1868 Robert F. Mushet, a metallurgist of Sheffield, 
England, made a momentous discovery. He found that a 

240 



THE HIGH-SPEED STEELS 241 

piece of tool steel which had cooled in the air was as hard 
as some of those which he had quenched. Being an investi- 
gator he set about discovering the reason for this experi- 
ence which was without precedent. Analysis showed that 
beside the usual constituents of tool steel this particular bar 
contained tungsten, a comparatively new metal. He experi- 
mented Avith some hundreds of mixtures and evolved an 
alloy, which, in tools, would stand up under machine speeds 
double those which could be used with carbon steels. These 
new alloys became known as "air-hardening" or self -hard- 
ening tool steels because they required no quenching. 

The principal application of these new steels was in the 
cutting of harder metal than it had before been possible to 
cut, and little attention, apparently, was paid to the getting 
of greater outputs by increase of machine speeds. 

At this point Frederick W. Taylor of "efficiency" fame 
appears upon the scene. While manager of the Bethlehem 
Steel Works in the nineties of the last century, he was 
working upon the efficiency investigations for which he later 
became so famous. During his investigations, with Maunsel 
White he experimented with many air-hardening steels to 
determine the best grades to use for their shop work. Get- 
ting some inconsistent results they determined upon and 
made what was a most extended and systematic investiga- 
tion, one so thorough and complete that Taylor and White 
have become part of the history of high-speed steels. 

They produced new compositions the quenching of which 
could be from temperatures greatly in excess of those which 
tool makers for centuries had held to be ruinous and which 
really are ruinous to carbon tool steels. The best results 
were obtained when the new steels were quenched by plung- 
ing in oil from close to their melting points — a dripping 
or "sweating" heat as it is called. This was something 
entirely new but it developed that after proper drawing, 



242 NON-TECHNICAL CHATS ON IRON AND STEEL 

steels quenched from these extreme temperatures, would 
stand up under lathe speeds as great as 200 or 300 feet 
per minute. 

Compare these with the miserable speeds of 20 or 30 feet 
per minute, which were the average performances of the 
best carbon steels. 

The secret of Taylor and White's treatment was not long 
in coming out and soon high-speed steel makers in Europe 
and America were vying with each other in production of 
finer and finer high-speed steels. 

The progress which has been made during the last twenty 
years and particularly during the past ten has been astound- 
ing. Improvement has followed improvement in composi- 
tion, manufacture and heat treatment, so that to-day, in- 
stead of the cut at 30 feet per minute, which was a high 
figure with carbon steel tools, the modern lathe or shaper 
tool often works at 300 or 400 or more feet per minute, and, 
with sufficient power behind it, at somewhat lower speeds 
plows out y 2 inch deep and % inch wide chips so fast that 
their removal to keep the machine clear is no mean problem. 
Often 2,000 pounds of the material per hour can be thus 
cut away with one tool. 

As suggested, the new steels do not suffer such loss of 
temper from the heat generated by the friction of the tool 
in the metal as occurs with carbon steel tools. In fact, tools 
of high-speed steel work best after ' ' warming up ' ' and they 
can run for a considerable period of time with the point of 
the tool red-hot, though such is not advisable. 

As is readily seen the essential property of the high- 
speed steels is the so-called "red hardness" which is the 
ability to retain hardness at red heat. This is several hun- 
dred degrees in excess of the temperatures at which the 
carbon tool steels quickly lose their "temper." 

As forecast by Mushet, the essential constituent of the 



THE HIGH-SPEED STEELS 243 

new steels is the metal, tungsten. But tungsten alone can- 
not give the desired property. Mushet, it will be remem- 
bered, was the metallurgist whose patents for the use of 
manganese in steel Bessemer was obliged to recognize to 
make his process a success, though the metal had earlier 
been used in crucible steel. The air-hardening property of 
Mushet 's steel was contributed by a happenstance com- 
bination of tungsten and this same metal, manganese. It 
later developed that tungsten and chromium were the best 
hardening elements and these have maintained their place, 
though refinements of the past few years have made use of 
vanadium, and, more recently, cobalt in addition. Usual 
amounts may be said to be tungsten 14 to 25 per cent, 
chromium 2 to 7 per cent, with vanadium y 2 to l 1 /^ per 
cent, and cobalt up to 4 per cent, perhaps. The carbon 
content is usually .6 to .8 per cent. Sometimes another 
comparatively rare metal, molybdenum, is used in high- 
speed steels in place of part of the tungsten, but its use 
does not seem to be on the increase. 

Manufacturers differ considerably in formulas. 

It will be noticed that at best there is left room for only 
70 or 80 per cent of iron in the alloy. From certain stand- 
points, the high-speed steels might not at first thought be 
called "steels" at all since carbon seems to be of so little 
importance. They might be considered to be low carbon 
alloys somewhat similar to the newer "stellite" (an alloy 
from which tools are made), which contains little or no 
carbon and no iron but is made up mainly of cobalt and 
chromium. They fit in, however, with the general and very 
comprehensive scheme of classification of the iron-carbon 
alloys which has been developing over a period of twenty 
years and there is no doubt among metallurgists and metal- 
lographists that, as is the case with the alloy steels de- 
scribed above, they are iron-carbon alloys — in other words, 



244 NON-TECHNICAL CHATS ON IRON AND STEEL 

steels — the properties of which have been greatly modified 
through the presence of the other elements. Carbon, there- 
fore, is an essential, though it is much less in amount than 
in the carbon tool steels. The hardening and softening 
properties, also, very definitely classify these alloys with 
the "tool steels." Stellite cannot be softened. 

As with the carbon tool steels, most of the high-speed 
steels are made by the crucible method, though a small but 
increasing amount is of late being produced in the electric 
furnace. After careful pouring into small ingots and cool- 
ing, the ingots are removed from the iron molds and 
"topped" to remove any "pipe" or unsound portion. 
Then, if without defect and satisfactory as to analysis, they 
are slowly and carefully heated to forging temperature 
and are hammered out into bars. By this method they are 
taken nearly down to the final size desired. The bars are 
finished by rolling to size. After careful annealing they 
are ready for shipment to the tool maker. 

When taking heavy cuts a tool of to-day may exert as 
much as ten tons' pressure against the metal it is cutting 
and the advent of this wonderful material for tools neces- 
sitated the building of immensely heavier and stronger 
lathes and other machines, which, alone, were capable of 
giving them power to do their work. The high-speed steels, 
therefore, have revolutionized metal-cutting practice and 
shop methods and have very largely aided efficiency. 



CHAPTEK XVI 
THE MECHANICAL TREATMENT OF STEEL 

Molten steel is practically always poured into upright 
molds of cast iron which shape it into long slightly taper- 
ing blocks of metal of square or rectangular cross-section. 
After the ingot mold has been stripped off, the still red-hot 
ingot cannot well be taken directly to the rolls, for, while 
the exterior parts may have the proper temperature for 
rolling, the interior of the ingot may still be liquid. The 
ingot, throughout, should be uniform in temperature when 
it is rolled. It is therefore put into a closed pit or fur- 
nace of proper temperature where the center of the ingot 
can be cooling while the outer portions are kept hot or 
are reheated if necessary, until all is ready for the rolling 
operation. 

It would take a "steel man" a long time to tell you all 
of the unfortunate things that can and do happen to such 
blocks or ingots of steel which influence their applicability 
to the purposes for which they are intended. You must 
have learned of the most serious of these — "pipes," 
"cracks," "segregation," etc., through reports of inves- 
tigations of broken railroad rails and accidents caused 
thereby. A word or two regarding these: 

In the ingot mold 'the outside of the steel ingot is, of 
course, the first to solidify. It may be hours after the 
freezing of the outer crust before the interior is able to 
cool sufficiently that it, too, can set. As steel, like most 

245 



246 NON-TECHNICAL CHATS ON IRON AND STEEL 



other metals and alloys, occupies less space when "frozen" 
than it does when molten, there must occur a hollow space 
in the interior since the crust is solid and cannot contract 
much. This hollow space usually takes the form of a more 
or less elongated cavity extending along the axis of the 
upper quarter of the ingot. It is called a "pipe." 

Then, too, the metalloids of the steel do not always stay 
where they belong. Even if the steel has been of a uni- 
form chemical composition when poured, the interior por- 
tions of the ingot after cooling will be found to have a 

greater amount of sulphur, phos- 
phorus and carbon than parts which 
are nearer the surface. Such gath- 
ering together of constituents of the 
steel is known as "segregation." 

With the development of the steel 
industry and the demand for greater 
and greater tonnages, ingots have 
been made larger and larger. Pip- 
ing, segregation, etc., are very natu- 
rally accentuated in the large masses 
of steel. 

Much "gray matter" has been ex- 
pended in attempting to overcome 
these and other defects to which large steel ingots are liable. 
Covering the molten ingot top with charcoal; filling in be- 
fore complete solidification with additional molten metal; 
and keeping the ingot top molten by application of powerful 
gas flames have been, perhaps, the most useful methods. 

But, even so, piping and segregation have not been com- 
pletely prevented, though great improvement has resulted. 
The usual way around the difficulty is to make certain 
that only the bottom (or best half) of each ingot is used 
for the most important products, such as locomotive and 




Pipe and Blowholes in 
an Ingot of Steel 



THE MECHANICAL TREATMENT OF STEEL 247 

car axles, firebox and boiler plates, rails, etc. The next 
or third quarter or a little more is utilized for products 
which go into less exacting service. These may be plates 
for ordinary water tanks, for flooring, for ship plates, etc. 
The top part which contains the pipe is cut off and goes 
back to the furnace to be remelted. It is termed ' ' discard. ' ' 

The big steel makers themselves shape most of their 
steel into such finished products as rails, plates, rods, and 
wire. Some of it is by them reduced from the ingot into 
intermediate "blooms," "billets," "bars," etc., and sold in 
this form for the manufacture of axles, drop forgings and 
the hundreds of products which we each day see. 

It is a very fortunate circumstance that at a cherry-red 
or white heat the carbonless irons and most of the steels 
can be quite easily fashioned into products. As is well 
known to us the most usual methods of mechanically shap- 
ing these metals while hot are by hammering, by rolling 
and by forging in a press. 

With sufficient power and proper appliances, soft and 
medium steel to a considerable extent can be fashioned 
cold, but, of course, in this condition its resistance to re- 
shaping is immensely greater. The cold treatment of these 
metals is usually some form of tube or wire drawing. 

Certain other methods such as extrusion, spinning, etc., 
are also in use, and, through them, some otherwise diffi- 
cultly formed products are made. 

In one of the earlier chapters we saw that annealing- 
refines (make finer) the grain of a steel casting and im- 
proves its physical properties. Annealing for refining pur- 
poses is practiced with other steel products also, and with 
just as effective results. 

However, the mechanical shaping of steel while at cherry- 
red or at a white heat much more materially refines the 
grain while helping the strength and greatly increasing the 



248 NON-TECHNICAL CHATS ON IRON AND STEEL 




No. 69a. Photomicrograph op Cold-Drawn 

Steel Wire Showing Distortion of the 

Crystals from Cold Working 

Hot Working does not produce distortion 
but makes the grain finer. Annealing relieves 
this distortion to a great extent. 

(Magnification 70 Diameters.) 



ductility of the alloy. 
Steel which has been 
hot-forged or rolled is 
said to have been "hot 
worked. ' ' Steel usually 
is "hot worked," for 
"cold-working" meth- 
ods are not so generally 
applicable and the prod- 
uct is more liable to suf- 
fer under the more 
drastic treatment. The 
amount of "hot-work," 
at proper temperatures, 
that low and medium 
carbon steels will stand 
with improvement of the grain and physical properties is 
considerable. 

As we must anyway shape the 
metal into useful implements 
and other products, it is fortu- 
nate that the quality of the 
metal is benefited by the process. 

Forging 

Undoubtedly the earliest 
shaping of ferrous (iron) met- 
als was by hammering the small 
balls of metal into bars, spears 
or swords. Presumably it was 
done with stone hammers which 

later had to give way to hammers made of iron. These had 
sufficient hardness to serve the purpose well. 




THE MECHANICAL TREATMENT OF STEEL 249 



For hundreds of centuries the shaping of iron, steel and 
the other metals into tools and weapons must have been 
done by such forging methods. It is not difficult for us to 
picture the early 
smiths at their work, 
laboriously and yet 
very skillfully ham- 
mering into spear- 
heads and sword- 
blades the lumps of 
iron or Wootz Steel 
which they had made 
in their crude fur- 
naces. 

In much the same 
way, though on a con- 
siderably larger scale 
and with heavier and 
better hammers and 
tools, was the same 
work done up to the 
time of the invention 

of Cort's rolling process — about 1783. Various styles of 
hammers were used, some with a spring pole attached to 
raise them for the next stroke which was delivered by foot 

power, others known 
as "helve" 
" shinglin^ 
hammers gave pe- 
riodical blows as 
teeth on a revolv- 
ing wheel lifted and allowed the hammer heads to fall. The 
heavier ones often gave as many as seventy-five and the 
lighter ones which were used for "tilting" (forging) shear 




The Old Oliver Foot-Power Hammer 




or 

7) 



An Old Forge Hammer 



250 NON-TECHNICAL CHATS ON IRON AND STEEL 



steel into bars or implements as high as three hundred blows 
per minute. 




The Sqoeezer Was Sometimes Used in Place of the Hammer 

Though Cort's rolls very materially aided in the shap- 
ing of balls of iron from the puddling furnace into bars, the 




The Old Tilt Hammer 



hammering or forging method remained the one by which 
finished iron and steel articles were made. 



THE MECHANICAL TREATMENT OF STEEL 251 



About 1835 it happened that a very large propeller shaft 
for a new ship was desired. Being so large, no one was 
found who could forge it until the matter was put before 
an English iron-worker named James Nasmyth, who had a 
reputation for ingenuity. Nasmyth roughly sketched out 
an immense hammer which he proposed to operate by steam. 
There was no 
opportun- 
ity to build it, 
however, for 
the propeller 
shaft never 
was ordered. 
But the idea 
of the steam 
hammer got 
to certain 
French engi- 
neers, w h o 
construct- 
ed one which 
Nasmyth 
came upon 
during a visit 

to a French A Belt-Deiven Power Hammer of To-day 

iron works. 

Nasmyth realized the importance of his invention, which, 
luckily, the Frenchmen had not attempted to patent. A 
patent was granted to Nasmyth. 

To most of us the steam hammer, still little changed in 
essentials, is quite well known and some of us have wit- 
nessed the cracking of an egg without breaking the egg cup 
which held it. The adjustment and regulation of these 
mammoth hammers is so nice that with almost successive 





Two Board Hammers and Trimming Press 
252 



THE MECHANICAL TREATMENT OF STEEL 253 

blows a skillful operator can flatten a piece of iron and 
then break the crystal of a watch without otherwise in- 
juring the timepiece. Needless to say, the steam hammer 
has proved to be the only efficient hammering device for 
forging large pieces. 

But whether made in the small way of the village black- 
smith, by the larger helve, tilt, Bradley, or by the monster 
steam hammer, each forging, unless made in a die, must 
be considered to be specially formed and no two pieces, 
when finished, are exactly alike. They are always "hand 
made" articles. 

Drop Forgings 

Many years ago, what are known as duplicate or inter- 
changeable parts, therefore, were quite unknown and it is 
related that parts of the famous English Enfield rifle were 
made in various parts of the civilized world, shipped to the 
Tower of London and there assembled. But during as- 
sembly, the various pieces had to be filed and carefully ad- 
justed by hand because no two parts were exactly alike. 
But the "Yankee tool makers" of New England solved the 
problem by forging the pieces of which many duplicates 
were necessary in a "die" or impression in a block of steel. 
The forged pieces, of course, took the exact impression of 
the "die" and successive pieces thus made were alike in 
size and shape. From finished duplicate parts which went 
to London from the New England states, the Enfield rifle 
was assembled with very little final finishing of the "cut 
and try" variety. 

Done at first with the die on a blacksmith's anvil and 
with a light hammer, this promising method soon developed 
expert "die-sinkers" (die makers), also ingenious men of 
whom the term l ' Yankee Tool Makers ' ' is self-explanatory. 

In connection with this work what are known as "drop 



254 NON-TECHNICAL CHATS ON IRON AND STEEL 

hammers" came to be largely used. Of these an impor- 
tant type were the "board hammers," in which the heavy 
steel hammer-head was attached at the bottom end of a 
vertical board set between pulleys. As the pulleys squeezed 
and revolved against the board it was carried up between 
them and dropped, when the pulleys loosened it at what- 




Nasmyth"s Steam Hammer Revolutionized Steel Working 



ever height was desired. Kapidly and periodically as- 
cending and dropping upon the anvil beneath, it quick- 
ly forced the white-hot iron into the "die" upon the 
anvil, forming what have since been known as "drop forg- 
ings." 

Commonly the hammer face itself carries the impression 
of the upper part of the article to be formed, i.e., there is 




Modern Forging of an Automobile Crank Shaft 



255 



256 NON-TECHNICAL CHATS ON IRON AND STEEL 

an upper "die" on the hammer and a lower one on the 
anvil. 

"Fins" were of course, left all around where the excess 
metal was squeezed out from between the upper and 
lower dies. It shortly developed that a second pair of dies 
shaped for trimming could clean the forging of this ex- 
cess metal; which is so well known under the appellation, 
"flash." 

Nasmyth's steam hammer, also, has been used very 
largely for drop-forging work. 

A "cast" metal is not and cannot be as dense, free from 
holes, sponginess or other defects or as strong as "worked" 
metal. While often not as cheap as castings as far as cost 
of production goes, " drop-f orgings " are usually consid- 
erably superior to them and are to be preferred. How- 
ever, it does not pay to make dies unless for many pieces. 
One or several "castings" can be made without great 
expense. 

Forging of Large Pieces by Hydraulic Press 

Of late years much forging has been done, not by the 
hammer which gives such a sudden, superficial blow with 
shallow working of the piece, but by hydraulic or other 
press, which very slowly squeezes the hot piece to smaller 
and longer shape. Sir Henry Bessemer was one of the first 
to realize the advantages of and make use of the press for" 
steel working. 

Unlike the hammer the press exerts a deep working of 
the piece which can be seen to flow throughout under the 
stress rather than in surface only as occurs under the ham- 
mer. This is very desirable as the interior, which is known 
to have much coarser grain than outer parts, particularly 
needs to be "worked." In plainer terms the press seems 
to knead the mass much as the bread-maker kneads dough, 




257 



258 NON-TECHNICAL CHATS ON IRON AND STEEL 

while the hammering method simply batters down the out- 
side. At a glance an experienced eye can tell from the 
appearance of the end of a forging whether it has been 
pressed or hammered. 

Pressures as high as 8,000 pounds per square inch are 
used in hydraulic presses, though much lower pressures are 
more common. 

Forging vs. Rolling 

Though we have not yet considered the rolling mill or its 
products, we understand that, in general, only products of 
regular and uniform cross-section and of considerable 
length can conveniently be rolled. Where they can be ob- 
tained of satisfactory shape and size, steel products formed 
by the rolling process are highly desirable and are usually 
cheaper than those which are produced by the forging 
process. Compared with those made by the rolling process, 
forged products are usually quite costly in labor and time. 

Boiling mills, however, cost immensely more to build 
and equip than do plants installing even the steam ham- 
mering outfit, so the rolling process cannot pay except for 
such articles as are demanded in great quantities. Articles 
of irregular and odd shape must, of course, be forged and 
here, especially for very small articles, the drop-forging 
process is available and highly satisfactory where enough 
pieces of one kind and size are wanted to pay for the requi- 
site dies. 

Forged articles have another advantage which we should 
not overlook. The physical properties which are imparted 
during forging are somewhat superior to those which the 
rolls bestow. The physical properties shown by the latter 
are very satisfactory, however. 



CHAPTER XVII 
THE ROLLING PROCESS 




Early Rolls 



After invention of the puddling furnace with its rather 
large yield from the standpoint of those days, Cort about 
1783 found the hammering method unsatisfactory for his 
purposes and rolls were devised by him to facilitate work- 
ing of the larger balls of iron which his furnace pro- 
duced. 

His rolls were provided with a series of grooves which 
systematically reduced the balls of iron to pieces of longer 
and longer length and proportionally decreasing diameters. 
They were power driven and served very well as long as 
iron and steel were made in quantities no larger than those 
which were produced in the puddling and crucible fur- 
naces. 

Quite naturally there was little or no change in the es- 
sentials of rolling mill design until it was forced by the in- 
vention of the Bessemer steel-making process. With that 

259 



260 NON-TECHNICAL CHATS ON IRON AND STEEL 




occurrence trouble began. The open-hearth process fol- 
lowed, and, with the increasingly large steel outputs of 
mills using these processes, necessity after necessity de- 
veloped which resulted in the highly developed rolling mills 
of to-day. 

The "Two-High" Mill 

The mill as invented by Cort had but two rolls and these 
were actuated by a fly wheel. Turning in one direction 
continually, the rolls allowed the piece being rolled to go 
through in only one direction, i.e., it had to be returned 
from the rear to the front side of the mill after every pas- 
sage, usually called "pass." This was done by the 
"catcher," a brawny man at the rear of the mill, seizing 
the piece, lifting one end bodily to the top of the upper 
roll over which it was carried back with more or less dif- 
ficulty and awkwardness to the "roller," who, from the 



THE ROLLING PROCESS 



261 



front, seized and entered it again into the next succeeding 
or smaller groove of the rolls. 



The "Three-High" Mill 




Two-High Rolls and Effect on the Piece 



In 1857 John Fritz 
was watching his men 
at their slow and fa- 
tiguing work at the 
two-high mill of the 
Cambria (Pa.) Iron 
Works. The thought 

struck him that by adding another or third roll at the top, 
the piece could also be given a pass on every trip back 
to the roller in front. The rolls would of course pull it 

through, the work would be less 
severe on the men, and, receiving 
passes in both directions, the 
piece would receive the full num- 
ber in approximately one-half of 
the time which was then required, 
and, more important than all else, 
it would not have nearly so long 
a time to cool and could be fin- 
ished at a more desirable temper- 
ature — a great advantage. 

Strange to say the idea was 
immediately pronounced imprac- 
ticable when he mentioned it and 
it was necessary for him to go 
through a long fight to obtain 
permission to make a trial. 

The experiment was from the first successful but the 
mill burned one Saturday night, having supposedly been set 




Action of Three-High Rolls 



262 NON-TECHNICAL CHATS ON IRON AND STEEL 

afire by workmen who feared loss of their jobs. Rebuilt 
and manned by new workmen it ran with success. 

The succeeding ten years saw the "three-high" type of 
mill come into extensive use both in America and Europe. 
Elevating or tilting tables have since been provided which 
mechanically raise the piece to the upper rolls, thereby re- 
lieving the workmen of this duty, which, with the great in- 
crease in size of ingots and pieces rolled soon became very 
arduous. To-day the "three-high" mill is just as impor- 
tant as ever. 

The Reversing Mill 

Having a fly wheel for the storing-up of power, the rolls 
must keep turning continuously in the established direc- 
tion. In England, Nasmyth — the same man who invented 
the steam hammer — suggested that the fly wheel be dis- 
pensed with and the two-high rolls reversed after each pass. 
The piece would go back to the roller's side receiving work 
in a regular pass on the way, just as in the three-high re- 
turn. The idea was developed by Mr. Eamsbottom of the 
London and Northwestern Railway Company. By the use 
of powerful enough engines the desired end was accom- 
plished and this type is now quite generally used for very 
heavy ingots which it is not economical to lift by tilting 
tables in the three-high mill process. There are certain 
other advantages also. 

The above are the three general types of mills. 



"Breaking-Down" the Ingot 

Whether it is to be sold in intermediate shapes or fur- 
ther rolled down into a finished product, all ingots have to 
be "cogged" or broken down into intermediate-sized slabs, 



THE ROLLING PROCESS 



263 



blooms or billets, for an ingot contains altogether too much 
steel for any single plate, rail, rod, or other finished 
product. 

The cogging or first rolling is accomplished in one of the 
three types of rolls already described but now more gener- 
ally in the reversing mill. 

When the tongs of the big overhead crane have lifted 
the white-hot ingot out of the soaking pit it is run back 
and forth 
through the 
rolls which 
are forced 
nearer and 
nearer to- 
gether by the 
11 screw- 
down" man 
so that the 
piece continu- 
ally becomes 
thinner and 
much longer 

Willi eacn Ingot Coming Out op the "Soaking Pit" 

pass. Tables 

made up of small rollers geared together receive the long 
piece as it emerges from the rolls. After each pass they 
bring the piece back to the rolls which are now turning in 
the opposite direction. The table on the other side re- 
peats the process, the piece being regularly turned on edge 
or slid from one side of the rolls to the other by steel 
guides which can be raised up between the rollers of the 
tables where desired. The direction of these as well as of 
the rolls themselves is controlled through levers by two 
or three men standing at one side of the mill. 



'rajl^F r V'-jfiUPSS 


■ 


• ^ _ v - - 


m 


1 L": 


>._J>- -~ .■■■■ 


*m 


fcl" "\ 


^^iH ; '-"■P^T^^" _A-^ •' -*j 



264 NON-TECHNICAL CHATS ON IRON AND STEEL 




Reversing after each pass, with the big ingot apparently 
turning and sliding itself into the most advantageous po- 
sition for the next entry, the big engine, mill and roll-train 

seem almost 
human. 

The Rolling of 
Steel Plates 

It is mani- 
festly impos- 
sible in the 
space at dis- 
posal to give 
in much detail 
the rolling of 
many of t h e 
better known 
products. 
Fortunately it is not necessary, for after description of the 
making of plate, pipe and tube, and of rod and wire, the 
rolling of other forms such as rails, bars, and- the struc- 
tural shapes, 
I beams, chan- 
nels, angles, Z 
bars, etc., can 
well be im- 
agined. 

From the 
contract de- 
partment to 

the mill clerk come the orders for plate, with detailed list 
of sizes and thicknesses, and definite specifications of qual- 
ity in terms of chemical and physical requirements, etc. 



Ingot in the Rolls 




Steel Billets for Forging or Other Purposes 



THE ROLLING PROCESS 



265 



After studying these, the clerk makes requisition upon 
the open-hearth furnace for such tonnages of steel of vari- 
ous compositions as he estimates will give him sufficient 
stock for his purposes. As soon as possible the steel is 
made and poured into ingots which are transferred to the 
soaking pits of the slabbing mill there to await disposition 
as soon as the chemical laboratory has made analysis of 
the sample taken and has reported by telephone the result 
to the clerk 
who ordered 
the material. 
If close 
enough to the 
composi- 
tion he order- 
ed, he sends 
to the slab- 
bing mill his 
requisi- 
tion ordering 
them to roll 
and cut the 
four or six in- 
gots of the 
"heat" into 

slabs of definite weights, each one designed for a plate on 
a - customer's order. 

The clerk at the slabbing mill determines to what width 
and thickness each ingot shall be rolled and in what vary- 
ing lengths it is to be cut to furnish slabs of the definite 
weights ordered in the requisition. 

After rolling the ingot down to proper width and thick- 
ness, the "piped" end is cut off and "discarded." Slabs 
are cut and piled in regular order on a little flat steel car 




Rolling Ingot into Slabs 



266 NON-TECHNICAL CHATS ON IRON AND STEEL 



on which they are pulled, still red-hot, by the shrieking little 
dummy engine out from the slabbing mill, through the yard 
and to the plate mill furnaces, into which they are charged 
in proper order. Here they remain until they are again 
white-hot and the plate mill roller is ready for them. . 

Meanwhile record sheets giving the heat number, the 
number of the ingot and the weights of the slabs in the or- 
der in which they were piled come to the plate mill clerk. 
From these and the results of analysis of the steel he makes 
out the rolling orders for the plates to be manufactured. 

You have 
heard how 
difficult it is 
to g e t solid 
ingots and 
how the top 
eighth (or 
some times 
more) of an 
ingot is usu- 
ally "piped" 

and discarded. Now slabs from the balance of the ingot 
were piled on the car and have been charged in the plate 
mill furnace. Those from the upper part of the ingot (next 
to the discarded part) are used for the less exacting qual- 
ities of plate. Only the bottom half of the ingot, which of 
course is the solidest and best, goes into the higher grades 
of plate, such as "fire box," the choicest grades of "flange" 
steel, etc. The third quarter goes into flange stock, ' ' ship ' ' 
and "tank" plate, the latter representing miscellaneous 
lower-priced plate which may be used for water tanks, steel 
flooring, etc. Steel known as "fire box" of course must 
be of very high grade. It is used for parts of locomotives, 
etc., which come in contact with and likely will suffer de- 




Slabs from Which Plates Are Rolled 



THE ROLLING PROCESS 267 

terioration from flame, smoke, etc. The best " flange" goes 
into boiler plates and other products which have to stand 
considerable bending to shape. 

In making out his rolling orders the clerk sees that each 
numbered slab is ordered rolled only into a product for 
which it is well suited. He has to take into consideration 
the chemical composition, the probable strength and other 
physical properties which were definitely named in the 
specifications of the customer's order. And, as the physi- 
cal properties of such steel are mightily affected by tem- 
perature and speed of rolling and by rapidity of cooling, 
he must know mill practice and constantly keep in touch 
with the results which the physical testing laboratory is 
getting from bars sheared from such of his plates as have 
been "pulled" for customers or the inspectors who repre- 
sent them. 

When hot, the slabs one by one and in regular order 
come to the rolls from the furnace. Following his rolling 
orders the roller and his helpers put each slab back and 
forth through the plate mill rolls, first drawing it out to a 
width a few inches greater than the plate to be sheared 
from it, and then turning it a quarter around, they draw 
it out in the rolls until it has come down to the proper thick- 
ness or "gauge." 

If the clerk's computations have been correct the plate 
will now have the proper length. However, he may have 
ordered a slab of insufficient weight to make it, particu- 
larly if the rolls have become much worn. 

It will hardly be realized how much the width and thick- 
ness of the plate ordered have to do with the "percentage" 
of trimmed plate which the mill will get out of the slab 
ordered. There is a "fish tail" on each end of a rolled plate. 
On a thin, wide plate this becomes rather serious. 

Wherever possible the clerk puts two or three plates end 



268 NON-TECHNICAL CHATS ON IRON AND STEEL 



to end and perhaps narrow ones side by side, but he must 
not exceed the width which the ''shears" can "split" nor 
give the mill such a long plate that it will become too cold 
to roll or too long to be conveniently handled. 

For diversion the mill men take delight in throwing an 
extra amount of salt upon the plate to rid it of scale when 
nervous visitors have come as close to the rolls as their 
conductor through the mill will bring them. The explosion 
which comes from the usual amounts is much intensified and 

it is not at all 
out of the or- 
dinary to hear 
shrieks from 
the women 
and to see 
surprised and 
somewhat dis- 
mayed men 
among the 
visitors. 

Plate mills 
are usually 
t h r e e-high 
with tables of small rollers on each side which tilt to feed the 
plate into the rolls and to receive it on the other side from 
which it is fed in again, either above or below as the case 
may be. As the plates must be flat, perfectly plain rolls are 
used. For plates which are very wide these rolls may be 140 
inches or more long and perhaps three feet in diameter. 

The rolls, of course, are kept flooded with water to keep 
them cool. At first thought one would think that the water 
would cool the plates which are being rolled. It does not 
materially do so, however, the extreme heat apparently 
keeping the water from coming in actual contact with them. 




An 84-inch Plate Mill 



THE ROLLING PROCESS 



269 



Thus they are rolled down from the three-inch thick slab 
to 3/16", 1,4" or %", and from 6", 8", 10", or 12" slabs into 
W', %" or possibly 1" or 1^4" plates. 

All plates must be rolled very accurately to gauge, allow- 
ance of variation often being not over one or two hun- 
dredths of an inch. The roller must be a man of experi- 
ence and of very good judgment for slabs for almost any 
plate may come of any one of several thicknesses and 
lengths. He must know his temperatures, speeds of roll- 
ing and the 
amount of re- 
duction given 
with each 
pass, and, 
particu- 
larly in case 
of thin, wide 
plates, the 
condition of 
his rolls, 
which after 
two or three 
days' wear 
will produce 

plates thicker in the middle than at the edges. As the 
"screw-down" man on top screws the rolls together a 
little with each successive pass and the "hookers" un- 
der the roller's direction keep the plate entering the 
rolls properly, he must with his very accurate gauge 
measure the thickness of the plate as it nears com- 
pletion. Especially when plates are ordered and paid 
for by average weight per square foot must he judge 
accurately the thickness of the center of the plate 
where he cannot measure, and pull down the edges enough 




The Rolling op Plates 



270 NON-TECHNICAL CHATS ON IRON AND STEEL 

that the finished plate when sheared will average right. 

It is fortunate for the steel mill men of this country which 
does not know the advantages of the metric system that a 
steel plate one inch thick weighs very close to 40.8 pounds 
per square foot. This is an easy figure and the clerk, roller, 
hot bed foreman, weighers and all concerned "think" in 
terms of a plate one foot square and one inch thick. One- 
half inch plate, therefore, weighs 20.4 lbs.; y^", 10.2 lbs.; 
and 3/16", 7.66 lbs. per square foot. 

As will be seen when we consider wire drawing and cold- 
drawn seamless tubes, the strength and other physical prop- 
erties of steel depend first, upon composition, and, secondly, 
upon temperature at which they are hammered, rolled or 
otherwise "worked." Therefore, plates can be much modi- 
fied in physical properties by finishing at chosen tempera- 
tures. A steel containing .19% of carbon and .45% of man- 
ganese, for instance, which in one inch plate should give 
a tensile strength of around 55,000 pounds per square inch, 
58,000 pounds in y 2 " or 62,000 pounds in }4" when finished 
at usual temperatures, by slightly "colder rolling" can be 
made to show a considerably greater strength. Of course, 
the ductility is somewhat reduced, but, with a moderate 
amount of cold rolling, it will not be enough to do harm. 

All of these and many other details must be not only 
kept in mind but become second nature to the plate worker. 

After the final pass the plates go upon the "hot bed" 
where they are laid out side by side in the order in which 
they have been rolled. They must now have marked out 
upon them the boundaries of the smaller plates or pieces 
into which they are to be cut. From a duplicate of the 
roller's sheet the hot bed foreman marks upon the end of 
each plate what is to be laid out and boys or men wearing 
shoes with thick soles of old belting or other cheap non-con- 
ducting material go upon them with chalk and "squares" 



THE ROLLING PROCESS 271 

which are somewhat similar to the carpenter's square but 
having "legs" six and twelve or fifteen feet long. Though 
the soles of their shoes smoke from contact with the still 
hot plate, they very quickly and accurately mark out upon 
its surface the design which the hot bed foreman has 
signified. 

Usually the plates laid out are rectangular and of stand- 
ard size but often the boys have to lay out pieces of odd 
sizes and shapes, and sometimes, what are known as 
"sketches" have to be drawn using arcs, chords, radii, etc., 
as the student in geometry draws his geometrical figures. 
Round plates for boiler heads, tank ends, etc., in plate mill 
parlance are termed "heads." These are marked out with 
string and a piece of chalk. A boy with a pot of white 
paint follows and paints on the surface of each piece laid 
out its size, thickness, the customer's name, the order num- 
ber and heat number. That the plate can always be identi- 
fied, even after exposure to severe service or weather con- 
ditions, another boy with steel stamps follows and stamps 
into the steel the heat number. 

Cranes with magnets or hooks convey the long plates to 
the ' ' goose necks ' ' over the small rollers of which they are 
pulled to the shears where the powerful steam or hydrauli- 
cally-operated square-edged knife with ease trims the ends 
and irregular edges along the chalk lines into the sizes 
marked. Accuracy is everywhere necessary as *4" over or 
under ordered dimensions or a variation of two-hundredths 
of an inch in thickness may and probably will cause rejec- 
tion of a plate. 

After weighing and recording, the plates are conveyed to 
the shipping yard, where they are loaded by electro-mag- 
nets into cars for shipping. 

In the plate mill process above described plates any- 
where between 30 and 120 inches in width, say, can be rolled. 



272 NON-TECHNICAL CHATS ON IRON AND STEEL 



And as mentioned, the more or less irregular edges on the 
sides are "sheared" off. This extra allowance, which must 
be given, of course becomes "scrap." 

For plates which can best be rolled in long narrow 
lengths a "universal" plate mill is often used. This has 
vertical rolls just back of the two horizontal rolls, which 
are adjustable so that the plate can be regulated, not only 
as to thickness, but also as to width as well. Such mills 
give plates which have to be trimmed on the ends only, the 

sides being 
quite smooth. 
The rolling 
of plate has 
been described 
thus in de- 
tail that a 
slight con- 
ception can be 
obtained 
of the refine- 
ment and the 
minutia which 




Loading Plate from the Shipping Yard IS & necessary 

part of mod- 
ern mill practice. American outputs which have grown 
to as much as several hundred tons per twelve hour turn, 
require that every operation move along with "clock-like" 
precision. But with this immense tonnage and with all of 
the handicaps of occasional broken rolls and machine parts, 
electric crane delays, and illness of important men, the 
work must be and usually is kept up without serious de- 
lay. 

Modern metallurgical and rolling mill practice is a 
marvel. 



THE ROLLING PROCESS 



273 



Sheets 

Most plates are rolled from slabs which are about 36 
inches wide, but "sheets," which are plates less than 3/16" 
thick are rolled from much smaller-sized slabs known as 
"sheet bars." After "pulling out" into sheets these may 
be folded once or even more times, so that from two to eight 
thinner sheets are rolled at once. That they may not weld 
or stick together under the 
heavy pressure, they must be 
rolled colder than are single 
plates. They are later trimmed 
and pulled apart. Some mills 
start sheet bars of smaller size, 
for each sheet a separate piece, 
which, after drawing out some- 
what are piled, two, three, four 
or five high. With coal or char- 
coal dust — either dry or mixed 
with water — between them, they 
are heated and rolled, the char- 
coal and coal dust keeping them 
from sticking together. After 
annealing, pickling, etc., they 
may be cold finished in polished rolls or otherwise treated 
according to the purpose for which they are intended. 
After straightening some are galvanized, others are tinned, 
blued or painted. Most of them are sold "black," i.e., with 
no coating at all. Terneplate has a coating of 75% of lead 
and 25% of tin. 




The Rolling op Sheets 



The Rolling of Rails and Structural Shapes 

It will be readily understood after reading the above, 
that, instead of using plain rolls, mills for rolling steel rails, 



274 NON-TECHNICAL CHATS ON IRON AND STEEL 



I beams, channels, angles, Z. bars, rods, etc., must have 
grooved rolls. For these products the first pass will be 
through a groove slightly smaller than the bloom or billet. 
Successive passes will be through other grooves in the same 
set of rolls which will gradually make smaller and bring 
more nearly to the finished shape the piece being rolled. 

Before our eyes the white-hot bloom enters the three- 
high mill, goes backward and forward through the rolls and 

very shortly 
assumes the 
general shape 
desired. Each 
pass there- 
after brings it 
nearer to the 
finished 
shape. Rails, 
for instance, 
are rolled out 
from the 
blooms into 
one long rail 
perhaps 140 
feet in length 

which glides along like a huge snake to the swiftly revolving 
"hot" saws which are so spaced that four 33-foot rails 
are sawed from it at the same time. As the rails pass from 
the saws to the cooling bed they are marked by a revolving 
stamp. When cool they go to the straightening yard, are 
straightened, drilled, inspected and later loaded into cars 
for shipment. 

The production of all kinds of finished rolled iron and 
steel products in the United States during the past twenty- 
eight years is given in the following table which shows how 




Rail in the Finishing Rolls 



THE ROLLING PROCESS 



275 



extensive are our rolling mill industries and the rapidity 
of their development. 





Iron 


Plates 






Struc- 


All Other 


Total 


Year 


and Steel 


and 


Nail 


Wire 


tural 


Finished 


Gross 




Rails 


Sheets 


Plate 


Rods 


Shapes 


Rolled Prod. 


Tons 


1887 


2,139,640 


603,355 


308,432 






2,184,279 '* 


5,235,706 


1890 


1,885,307 


809,981 


251,828 


457,099 




2,618,660 


6,022,875 


1895 


1,306,135 


991,459 


95,085 


791,130 


517,920 


2,487,845 


6,189,574 


1899 


2,272,700 


1,903,505 


85,015 


1,036,398 


850,376 


4,146,425 


10,294,419 


1901 


2,874,639 


2,254,425 


68,850 


1,365,934 


1,013,150 


4,772,329 


12,349,327 


1903 


2,992,477 


2,599,665 


64,102 


1,503,455 


1,095,813 


4,952,185 


13,207,697 


1905 


3,375,929 


3,532,230 


64,542 


1,808,688 


1,660,519 


6,398,107 


16,840,015 


1907 


3,633,654 


4,248,832 


52,027 


2,017,583 


1,940,352 


7,972,374 


19,864,822 


1909 


3,023,845 


4,234,346 


63,746 


2,335,685 


2,275,562 


7,711,506 


19,644,690 


1911 


2,822,790 


4,488,049 


48,522 


2,450,453 


1,912,367 


7,316,990 


19,039,171 


1913 


3,502,780 


5,751,037 


37,503 


2,464,807 


3,004,972 


10,030,144 


24,791,243 


1915 


2,204,203 


6,077,694 


31,929 


3,095,907 


2,437,003 


10,546,188 


24,392,924 



Specifications and Inspection 

Customers, of course, have a right to see that their speci- 
fications are lived up to. Though years ago the mills per- 
haps intentionally sold to customers products which did not 
fulfill his specifications to the letter, it is not generally so 
to-day. Now the mills ' own inspectors are commonly more 
severe in their rejections of products than are the represen- 
tatives which the customers themselves send. Not only 
does the mill laboratory make careful and accurate analy- 
sis of each heat or batch of steel made, but, after its appli- 
cation to orders, pieces of plate, shapes or rails rolled from 
it are examined, gauged, and test bars of the steel are pulled 
in the physical testing laboratory. 

The mill rightly recognizes that it is for its own 
interest that the standard of its product be kept 
high. 

A trip through one of the large steel plants with its fur- 
naces, its blooming and slabbing mills, its rail, plate, struc- 
tural and rod mills is one of the most interesting that 
can be taken. If the visitor is not afraid of smoke or 
dust or of what seems to him an uncomfortable heat 



276 NON-TECHNICAL CHATS ON IRON AND STEEL 

on a warm day he will discover new worlds. No par- 
ticular attention is paid to the casual visitor to the 
plant, but, for those who show real interest, steel men 
have a warm welcome, from manager to the sample 
boys. 



CHAPTER XVIII 
THE ROLLING OF RODS 

Steel rods and what we will call large wires are rolled 
from billets which are long, and approximately square 
blocks of steel. The size and shape of the billets used vary, 
depending upon the process and the size of the rod to be 
rolled. Much of the finished rod is sold as such for various 
purposes for which round steel is desired and an immense 
tonnage of one of the smaller sizes is used as the intermedi- 
ate raw material from which wire is drawn. 

Rod mills have a very interesting history, which, by the 
way, is but one of several histories of the development of 
the iron and steel processes and products which should 
make us proud of the genius of man in the way of metal- 
lurgical, mechanical and business development. 

The Belgian Mill 

The first bars and rods were rolled in the old two-high 
mill, where, after each pass they were pulled back over the 
top roll and inserted into the next groove by the roller as is 
usual with the two-high mill. Then along came the three-high 
mill which probably resulted in greater advantage to rod 
rolling than to other lines, important, even, as it was to them. 

But long, thin bars or rods are quite pliable when at 
white or rolling heat and the "catcher" soon discovered a 
way by which he could save time and push up his tonnage. 
He skillfully caught the forward end of the bar as it came 

277 



278 NON-TECHNICAL CHATS ON IRON AND STEEL 



through, and, giving it a quarter twist, he inserted it in the 
proper return groove without waiting for the. whole bar to 
run through to his side before starting it on its return jour- 
ney. This, of course, was easily possible with the slow 
speeds then used. 

Naturally the rod coming through from one side and go- 
ing back to the other formed a loop. 

The roller, at the front, was not slow in discovering that on 
long rods he could do the same thing, so rods were soon reg- 
ularly going through three or more passes at the same time. 

It was soon 
found out that 
it was better 
to u s e a sec- 
ond set of 
rolls placed 
end to end 
with the first 
for the third 
and subse- 
quent passes 

as the roller had hardly room or time to loop the rod on 
the return and start his next one. This second set of rolls 
was connected on the same shaft and therefore made to 
run at the same speed as the first. It worked out that by 
use of such extra sets of rolls and an additional helper or 
two the same long rods could be running through as many 
as six or seven passes at once with a great saving in time. 

As it came from the final pass the forward end of the 
finished rod was seized in a pair of tongs by a boy who 
ran with it away from the rolls, stretching it out along the 
floor to cool. As the various sets of rolls were connected 
on the same driving shaft and revolved at the same speed, 
the loops which were formed between passes continually 




Wire-drawing of 350 Years Ago 



THE ROLLING OF RODS 



279 



grew longer. Here, too, boys with iron hooks were useful 
in controlling the loops. Later it was found advisable to 
have each succeeding mill speeded enough to take the rod 
as the preceding pair of rolls delivered it; then the loops 
remained of approximately constant length. 

To push 
p r o d u c - 
tion the mill 
was run fast- 
er and faster. 
As longer 
rods were 
rolled, a hand- 
operated reel 
was devised 
to which the 
boy attached 
the forward 
end of the rod 
while another 
turned the 
reel. But the 
speed of the 
mill was limit- 
ed mainly be- 
cause of the 
slow reel and 
the awkward method of getting the rod attached to it. 

The Bedson Continuous Mill 

About 1867 George Bedson of England, invented the first 
' ' continuous ' ' mill. 

Instead of looping the rod around and back through the 
rolls he put several sets of rolls each in front of the other 




Plan of a Modern Looping Mill (The Garrett Mill) 



280 NON-TECHNICAL CHATS ON IRON AND STEEL 

with every other pair vertical. This alternate horizontal 
and vertical roll arrangement was necessary because the 
reduction of the billet or rod in any pass can be only in a 
direction perpendicular to the axis of the rolls. The roller 
and catcher had given it a quarter-turn twist each time they 
started it into the two-high rolls. Bedson's successive pairs 
of rolls were set close together, each pair being speeded 
enough that it took the rod exactly as fast as the preceding 
pair delivered it. The billet or rod, therefore, traveled 
through them in a straight line. 

This continuous process was, of course, of great advan- 
tage in that considerable speed could be attained and there 
was not the rapid cooling nor the opportunity for loss by 
scaling from exposure to the air which occurred with the 
long loops of the Belgian Mill. It was a great advance, 
but the speed was yet held down by the finishing pass and 
the inability of the reel to coil the rod fast enough. 

The greatest development came through the inventive 
genius of two men, Charles Morgan and George Garrett, 
who developed the two separate types of mill which have 
made the rod rolling industry what it is to-day. The work 
of both was done in this country. 

The Morgan Continuous Mill 

Morgan's also was a continuous process. The billet was 
put in at one end of a new type of heating furnace which 
Morgan devised, and was gradually pushed along to the 
other end. From this second or outgoing end, the long, 
narrow, white-hot billet went through several pairs of two- 
high rolls set close together, each successive pair having 
smaller grooves than the one preceding it, so that, after 
traversing these several pairs of rolls, the rods emerged 
from the last pair finished, having traveled in a straight 
line through them. 



THE ROLLING OF RODS 



281 



Hand reeling was much too slow for Morgan who in- 
vented two different types of high-speed automatic reel 
which, in the highly speeded mills of to-day, receive and 
coil wire coming from the finishing passes at speeds of over 
one-half mile per minute. It is stated that the billets and 
rods therefrom traverse the rolls so fast and the pressure 
is applied so quickly and so hard that the rods emerging 




The Billet Traverses the Morgan Continuous Mill at High Speed Emerging 
from the Last Roll as Finished Rod 

from the finishing passes are hotter than were the billets 
when they went into the rolls. 

As was explained, no reduction in thickness is brought 
about by the sides of the grooves in the rolls. Therefore, 
a bar or rod must be turned after each pass unless Bed- 
son's alternating horizontal and vertical rolls are used. 
This turning Morgan did in spiral tubes inserted between 
the successive sets of rolls, all of which were horizontal. 
These tubes operate as does the "rifling" in a gun barrel, in 
turning the rod. 



282 NON-TECHNICAL CHATS ON IRON AND STEEL 

In Bedson's mill, with its alternating horizontal and ver- 
tical pairs of rolls, it was possible to roll only one rod at 
a time. With Morgan's system, in which all rolls were 
horizontal, several rods could be traversing the mill side 
by side. 

With the high-speed reels and what are known as " fly- 
ing shears" in which billets or rods can be cut to any 
length while going at full speed, Morgan's mill had come to 
a high stage of development. It was practically automatic. 

The Garrett Mill 

While Morgan was developing his continuous mill, Wil- 
liam Garrett was improving the old Belgian mill. Garrett 
believed and insisted that with proper working, rods could 
be rolled from billets of much larger diameter and greater 
weight than the long narrow billets which had been used. 
He eventually did away with an intermediate rolling opera- 
tion by using larger billets. 

You remember that in the Belgian mill the "catchers" 
looped the rods back into the rolls. To do this work auto- 
matically Garrett inserted between the sets of rolls looping 
troughs which guided the forward ends of the rods around 
and into the next groove in the rolls. These troughs are 
called " repeaters." It was found that while they worked 
very well for looping the cross-sections known as the 
squares, they were less suitable for looping the oval sec- 
tions which were produced with every other pass. These 
were better and more safely done in the old way, i.e., by 
manual labor. They are generally so done to-day. With 
the Morgan high-speed reel, sloping floors to better take 
care of the loops, and with successive pairs of rolls each 
running at higher speed than the preceding pair, the Gar- 
rett mill has apparently kept pace with the Morgan. 

Each has its advantages and each is used for certain 



THE ROLLING OF RODS 283 

classes of work. For long continued runs on rod of one 
size the Morgan mill can produce more cheaply, its product 
is more uniform in temper and the loss from scaling is less 
as little of the rod is exposed while in the mill. As the first 
pair of rolls in the Morgan mill is set close to the furnace, 
less than one-quarter of the billet is in the mill at any one 
time and the forward end of the billet is on the reel as fin- 
ished rod before the last of the billet leaves the furnace. 
With any process something occasionally goes wrong so 
that the rod does not follow the path intended. In such 
cases misshapen or tangled rod results. Such spoiled bil- 
lets or rods are called "cobbles." With what is known 
as the " flying shears," which in the Morgan mill cuts the 
billet or rod while it is traveling at high speed, the rear 
part of the piece can be cut off and saved in case of cob- 
bling. On this account the Morgan mill is said to give less 
scrap than the Garrett. 

The Garrett mill, on the other hand, gives rod which is 
more uniform all along in shape and diameter and it has 
the considerable advantage that it is quickly adaptable to 
change of product; it does not require such complicated 
and nice adjustment as does the Morgan mill. So, despite 
the greater danger to the rollers from the circling loops 
about them, which occasionally become unmanageable, the 
Garrett mill is largely used. 



CHAPTER XIX 
WIRE AND WIRE DRAWING 

It may be rather disconcerting to some enthusiastic ones 
who assume that we Moderns have made all the progress 
that is worth while to learn that so many of our supposedly 
new products were far antedated. In the case of wire, 
again, we were antedated as much as 30 centuries. The 
wires which were produced by the Ancients, however, were 
usually of the noble metals, gold and silver. They were not 
drawn through dies as are the wires that we know, but 
were hammered into shape from long, thin strips of metal. 
The earliest use of our "drawplate" method of which we 
find authentic mention was in the 14th century in Germany. 
The wire was hand-drawn. Machine-drawn wire was being 
produced in England as early as 1565. 

In the United States the wire drawing industry had be- 
come pretty well established by the middle of the 17th 
century. As Cort had not at this time invented the rolling 
process for bars and rods, very uneven strips of metal only 
were available from which to draw the wires. But, even 
so, with our highly developed rod mills and our present 
very satisfactory No. 5 wire rod to begin with, our wire 
drawing methods are yet seemingly crude and show small 
advance compared with the very great progress which has 
been made in other lines of the iron and steel industry. 

Unlike the processes of forging, rolling, etc., drawing of 
wire is done cold. In this condition steel has its highest 

284 



WIRE AND WIRE DRAWING 285 

strength to stand the strain. The rod or wire is pulled 
through very hard cast iron or steel dies, the general pro- 
cess being well likened to pulling a rope through a small 
knot hole. 

As was seen in the rolling of plates, "cold working" 
raises the strength, lowers the ductility and embrittles steel 
more than does the regular " hot working" at the cherry- 
red or white heats which are usual in the forging and roll- 
ing processes. If the so-called "cold finishing" at very 
low red or black temperatures affects the physical proper- 
ties of plates, it can be readily understood that cold draw- 
ing of wire and of seamless tubes at ordinary temperatures 
of 70 to 100° F., must considerably accentuate the effects 
noted. So much is this so that drawn wires and tubes 
have to be frequently annealed, i.e., heated to a good red 
heat for a time between successive trips through the dies, 
annealing having the effect of off-setting the lowered duc- 
tility and increased brittleness which would cause the wire 
to break. In some cases the wire has to be annealed after 
each pass or draft, but oftener several passes are possible 
before annealing is necessary. This depends largely upon 
the quality of the steel used and the amount of ' ' reduction ' ' 
attempted in each pass. 

The raw material, No. 5 soft wire rod, which is about 
one-fifth of an inch in thickness, comes to the wire-drawing 
plant from the rod mill. This No. 5 rod is the thinnest 
which the mills have found it economical to roll, so further 
pulling down in size can best be done by "drawing." 

As all iron and steel materials which have cooled in air 
from a red heat are covered with a hard, brittle scale of 
iron oxide, the rod must first be "pickled," i.e., digested 
in hot, weak sulphuric acid, which, in 10 or 15 minutes so 
dissolves and loosens the hard surface that it can be readily 
jarred loose and washed off. By immersion in a vat of 



286 NON-TECHNICAL CHATS ON IRON AND STEEL 

boiling milk of lime, the pickled rod is given a lime coating 
which neutralizes any acid which remains, and, when dry 
materially aids in the lubrication of the wire while it is 
going through the dies. Thorough drying, called l ' baking, ' ' 




Before Drawing into Wire the Scale Must Be Removed from the Rods by 

"Pickling" in Acid 



is accomplished in the dry house at 300 or 400° F., from 
which the rod with soft, scaleless, lime-coated surface goes 
to the "drawing" benches. After rinsing free from the 
pickling acid, the wire is often allowed to acquire a soft 
film of rust by spraying it with water and keeping it wet in 



WIRE AND WIRE DRAWING 



287 



• 



the air for a short time before going to the lime vat. This 
rust or "sull" coat itself assists in the lubrication. How- 
ever, the color 
of the product 
is not as good 
as when the 
"sull" coat is 
not used, and 
such wire usu- 
ally goes into 
articles for 
which darker 
color is no 
drawback. 

The dies 
with more or 
less funnel- 
shaped holes 
of accurate 

diameter are set vertically. They are of extremely hard 
material in order to stand as long as possible the severe 
service with- 
out excessive 
wear, which 
sooner or 
later so en- 
larges the 
holes that the 
dies become 
useless. Then 
they must be 
removed and 

either discarded, or, in the case of steel dies, the holes re- 
duced by hammering and redrilled. Often the holes of 



Single Wire-Drawing Block 






A Wire-Drawing Die 



288 NON-TECHNICAL CHATS ON IRON AND STEEL 

worn cast iron and steel dies are enlarged to the next 
larger size and so used. 

The loose end of each coil of rod of wire is hammered 
or otherwise made smaller for a length long enough to be 
threaded through the hole in the die and firmly grasped by 
tongs or "pliers." The die being firmly fastened, the draw 



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The Drawing of Wire 



head, of which the pliers are a part, is drawn away until a 
sufficient length has come through that it can be attached 
to a revolving block or drum which thereafter continuously 
pulls the rod through the die and winds it into a coil about 
the block as it comes, at speeds as high as 400 feet a minute. 
As the rod passes through the box in which the die is 
fastened, besides its lime or sull coating it is sometimes 
provided and takes up other lubricants, such as soap, 
grease, or tallow. 



WIRE AND WIRE DRAWING 289 

The coil of wire is lifted off the drum and tied, or is re- 
drawn to wire of a smaller size. 

After from one to several drafts, depending upon con- 
ditions, the wire must be annealed for several hours, and 
again pickled to remove the scale formed, washed, lime- 
coated and dried. For wire which must undergo many 
reductions or passes, as must all small wires, several draw- 
ings, annealings and cleanings must be gone through with 
before it is down to the desired size. 

In order to work properly and not cut the die too fast, 
which would rapidly enlarge the hole and cause the rear 
end of the wire to be of different thickness than the for- 
ward end, the rod or wire must be of maximum softness. 
Either under-cleaning or over-cleaning will make the metal 
harsh, as, also, will under-baking in the dry ovens. These 
they endeavor to avoid in preparing the rod. 

Other lubricants may be used and certain finishes or col- 
ors given to the wires. Such are the various white to red 
coatings which come from using tin and copper sulphate 
solutions instead of lime coatings. This is more often done 
with fine wire than with thicker. Certain " patenting" 
processes make use of various methods of tempering wires 
by cooling in air after a last annealing. 

Not only are wires ordered to size but many times also 
of certain temper or grades of hardness and stiffness. 
These various tempers are determined largely by the chemi- 
cal analysis of the steel and the number of drafts after the 
last annealing. 

Piano wire is well known to have a very high strength, 
sometimes as high as 400,000 pounds per square inch. 
Spring wire is rolled and drawn from higher carbon steel 
than is ordinary wire, and, through heat treatment, the 
best properties are imparted to it. 

Besides being in this form used for miscellaneous pur- 



290 NON-TECHNICAL CHATS ON IRON AND STEEL 

poses, thousands of tons of wire are annually made into 
wire nails, staples, wire fence, barbed wire, etc, all of 
which products are of American derivation, with the pos- 
sible exception of wire nails. Even this, however, if not 
originally ours we have made ours through our great pro- 
duction. All are very speedily turned out by automatic 
machines into which the wire or wires feed. The product 
drops out into boxes below or is rolled into coils as is the 
case of the wire fence and barbed wire. The speed of the 
machines is so great that the eye cannot begin to follow 
the operation. 

Wire being so well known it is not necessary to speak of 
its uses, but it will be interesting to call attention to the 
very extensive production of this steel product. Of the 
32,000,000 tons of steel produced in 1915, for instance, over 
3,000,000 tons were rods and wire, and when we think of the 
length of small or even average sized wire that it takes to 
make a pound, a hundred weight, or a ton, some slight con- 
ception of the amount of wire produced and used comes to 
us. As the material for wire gauze and cloth, wire rope, 
cable, piano strings, springs of all sorts, pins, needles, nails, 
fence, barbed wire, and the myriad of other things, wire 
really is one of our great products. 

It was mentioned that piano wire had been made which 
had a tensile strength as high as 400,000 pounds per square 
inch, which is six or seven times the strength of an equiva- 
lent cross-section of steel rail or plate. Wire is undoubt- 
edly the strongest product which is made from steel. This 
is why wire rope or cable is so strong. It is made by twist- 
ing together many small wires. 

Though extremely recent from the standpoint of our 
world's history, the building of the famous Brooklyn 
Bridge by the Roeblings was far enough back that we 
likely have forgotten that each of the four big 15%-inch 



WIRE AND WIRE DRAWING 291 

cables is made up of 5,296 separate wires tied into a 
bundle. 

Undoubtedly the best preservative against corrosion for 
iron and steel is what is known as "hot galvanizing." Much 
wire is hot galvanized. In this process the wire is "pickled" 
in weak acid to remove scale, given a soft red coating by 
dipping in weak muriatic acid and drying. The strands of 
wire 20 or 30 abreast are run through a kettle of molten 
zinc. The wires are wiped smooth and free from excess 
zinc by pulling them through asbestos pads. A continuous 
coating of zinc is thus permanently left upon the surfaces of 
the wires which very effectively keeps them from rusting. 
Wires which have to stand severe weather conditions may 
not have the excess zinc wiped from them. Telegraph and 
telephone wires often have the thicker or unwiped coating. 

Very naturally the drawing of wire requires use of much 
greater power than the rolling of rod and the speed of draw- 
ing is nowhere near as great. Therefore the cost of wire 
is comparatively much greater than the cost of rolled prod- 
ucts. In the case of watch springs it was once computed 
that the product had to bring 50,000 times the cost of the 
steel from which the wire was drawn. 

"Continuous" wire drawing has not been so successful 
nor advantageous as was the continuous rolling of rods. It 
has been possible in a small way and with certain grades of 
the product to apply the continuous process, but, mainly on 
account of mechanical difficulties, continuous drawing of 
wire seems to be comparatively unimportant. 



CHAPTER XX 
THE MANUFACTURE OF PIPE AND TUBES 

Tubes of some sort have been in use by man since very 
early times. Nature provided the first ones in the way of 
hollow stems of shrubs, such as alder and bamboo. Some 
of these we saw in use by the early smiths conveying the 
blast of air from their goat-skin bellows into the crude clay 
furnaces built in the hillside. 

Tubes made of clay, stone, lead and bored logs were also 
used. Much later pipes made of cast iron came into rather 
extended use for the conveyance of water. The general 
use of gunpowder greatly accelerated the manufacture of 
small tubes which the smiths produced for gun barrels by 
hammering and welding together long, red-hot strips of 
wrought iron about round rods or "mandrels." About 
1815 illuminating gas came to be used in England for house 
lighting. This brought a demand for tubes of considerably 
greater length, which were first made by screwing or 
otherwise fastening together old gun barrels which were 
very plentiful at that period. 

The first patents for the making of welded pipe as we 
know it were taken out in 1824 and 1825, the latter for the 
butt-welding method of pulling a narrow iron plate, called 
"skelp," through a bell-shaped orifice which curled it and 
welded the edges together very much as is done to-day by 
this process. 

Our modern pipe of both butt-weld and lap-weld varie- 

292 



THE MANUFACTURE OF PIPE AND TUBES 293 



ties is manufactured either from wrought iron or from soft 
steel. 

The Butt-Weld Process 

From the double-refined puddled iron, in the case of 
wrought iron, or from billets of soft Bessemer or open- 




.^^m^L^i, jtf 1 



Eakly Water Pipes 

hearth steel, long narrow plates are rolled. The width 
and thickness of these plates, which are known as "skelps," 
are exactly such as will give pipe of the desired diameter 
and gauge. In order that 
the weld may be solid all 
along, the skelp as it leaves 
the rolls has edges not ex- 
actly square but very slight- 
ly beveled, so that the sur- 
face which is to form the in- 
terior of the pipe is slightly 
narrower than the other. 

After trimming the pieces of skelp so that each has 
one end with a sort of point where the tongs are to 
take hold, they are laid side by side in a heating fur- 




How Butt-weld Pipes Are Made 



294 NON-TECHNICAL CHATS ON IRON AND STEEL 

nace and left there until they have become white-hot* 
Just in front of the furnace is the "bell," with a second 
and slightly smaller one in front. With strong tongs the 
workman reaches into the furnace and fastens onto the 
pointed end of a piece of the white-hot skelp. Hooking 
the handle of his tongs into the draw chain the skelp is 
drawn through the first and second bell, the first bending 




Plates Called "Skelp" Are First Rolled 



it almost into tube shape, the second completing the opera- 
tion and pressing together the edges of the plate in the top 
of the bell so tightly that they weld. 

The pipe now goes through what are known as cross 
rolls, the axes of which are somewhere near parallel 
with the axis of the pipe. In these the pipe is rapidly spun 
around, surface-cleaned and straightened. Going up a cool- 
ing incline it goes to tables where the ends are cut off and 
the product inspected. 

A very important part of the inspection is the hydrostatic 



THE MANUFACTURE OF PIPE AND TUBES 295 




Charging Skelp into the Heating Furnace 

or water test. One at a time the pieces are tightly fitted in 
between two water-tight caps, water is turned into the pipe 






Drawing Butt-weld Pipe 



and gradually brought up to the testing pressure of 600 
pounds or more per square inch according to specifi- 
cations. 



296 NON-TECHNICAL CHATS ON IRON AND STEEL 

Pipes of diameters between %" and 3" are usually made 
by the butt-weld process. 

Lap-Welded Pipes 

Pipes larger than 3", and boiler tubes or other particu- 
larly high-grade welded tubes of 2" and over are usually 

' ' lap-welded. ' ' This process 
gives a considerably more 
reliable product than does 
the butt-welding process, for 
reasons which are readily 
seen. 

Skelp for lap-welding is 

rolled in just the same way 

as is skelp for butt-welding except that the edges are 

"scarfed" or decidedly beveled so that the two edges can 

make a considerable lap without increase of thickness of 




_Td 



How Lap-weld Pipes Are Made 




Bent Skelp for Lap-welding Being Charged into Furnace 



that part of the wall. These pieces of skelp are charged 
into the heating furnace just as occurred in the butt-weld 



THE MANUFACTURE OF PIPE AND TUBES 297 



process and, after coming to a white heat, they are drawn 
through a sort of bell or die which curves them so that one 
edge considerably overlaps the other. Back they go into 
the furnace to regain any heat that has been lost, for, to 
weld properly, the skelp must be hot enough that any scale 
which had covered it drips off. 

The welding rolls are very short rolls, almost ' ' sheaves ' ' 
or wheels, with 
concave edges of ex- 
actly the outside di- 
ameter of the pipe to 
be formed. Between 
these two rolls, at the 
end of a long straight 
bar, is a mandrel or 
projectile-shaped ball 
of high-speed steel 
over which the white- 
hot tube must be 
pushed. 

The reheated, 
curved skelp is pulled 
from the furnace and 
the forward end 
forced into the rolls 
which shoot it 

through and over the mandrel at high speed, forcing to- 
gether and welding under heavy pressure the overlapping 
edges of what was formerly the plate. Amid the noise and 
the shooting sparks an unsuspecting bystander is quite 
startled by the suddenness of it all. 

While still hot the pipes pass to "sizing" rolls which 
correct any variation in inside and outside diameters. The 
cross or straightening rolls next smooth and clean their 




The Lap-welding Rolls with Mandrel in 
Position 



298 NON-TECHNICAL CHATS ON IRON AND STEEL 

surfaces while straightening the pipes or boiler tubes. 

After the first trip through the welding roils, boiler tubes 
and certain other high grades of pipe go back into the fur- 
nace where they are reheated. They are again put through 
the welding rolls to make absolutely sure of a tight weld. 

After cooling, the ends of each pipe are cut off. Because 
of the "scarfing" of the edges and the great pressure of 
the rolls, it is difficult to tell where the welds occur, the 
thickness of the walls being practically uniform all around. 




Pipes in Sizing and Cross Rolls 

Lap-welded pipe of as great as 36" diameter has been made 
in this way. 

The water-pressure test is given to all lap-welded pipe 
as are certain tests for tensile and torsional strengths, and 
for ability to flatten without breaking. In the case of boiler- 
tubes, a piece is cut from each end of each tube, which must 
stand flanging or spreading "cold" and also must crush 
down endwise under the heavy pressure applied in the test- 
ing machine without fracture or opening of the welds. 

The pipe may be "threaded" to order or shipped as it 
comes from the testing bench. 



THE MANUFACTURE OF PIPE AND TUBES 299 




The Finishing End 



As remarked, both butt and lap-welded pipe is regularly 
manufactured from wrought iron and from steel. 




Hydrostatic Test of the Pipes 



It was suggested during the discussion of the manufac- 
ture of wrought iron, that, owing mainly to high labor costs, 



300 NON-TECHNICAL CHATS ON IEON AND STEEL 

wrought iron was with difficulty competing with the soft 
steels. Wrought iron is noted for its welding properties 
and it has always had its loyal admirers. Aside from its 
application as "bar iron" which always has been and still 
is in favor with many metal workers for miscellaneous pur- 
poses and its use as Swedish bar iron or low phosphorus 
melting bar by makers of crucible steel as a base for their 
product, wrought iron probably finds its next most favored 
place as a material for pipe as is shown by the table given 
in Chapter VI. 

"While not as strong as steel pipe under hydrostatic test, 
many pipe users insist that, presumably on account of its 
slag enclosures and cinder films which are supposed by 
some to surround and protect the fibers, wrought iron pipe 
outlasts steel pipe when used under conditions which induce 
corrosion. Others are as strenuous in their denial of this 
assertion and this subject of comparative wrought-iron-pipe 
and steel-pipe corrosion is still a very live issue. For many 
years this matter has been under investigation. Hundreds 
of tests have been made and discussed by learned societies 
and their committees. The laboratories and testing de- 
partments, too, of the large pipe manufacturers and their 
customers, have made extended investigations. 

However, the conditions under which pipe is used are so 
varied and the time required for any true and decisive test 
is so long that really conclusive results have not been forth- 
coming. With other materials, each condition and corrosive 
influence is largely a "law unto itself," and one wonders 
if such may not prove to be the case with these materials 
also. As suggested, a great quantity of published informa- 
tion giving comparative service tests is available for those 
who are particularly interested in this subject. How much 
of the decline in tonnage and in percentage of the total 
skelp produced, is due to the approximately 30% greater 



THE MANUFACTURE OF PIPE AND TUBES 301 

cost of wrought iron pipe and how much to satisfactory 
performance of its competitor must be left to you to judge. 

Fortunately pipe of both kinds is available, meanwhile, 
and one can get whichever he prefers. 

The uses of pipe are almost innumerable. Great quan- 
tities are used for conveyance of water, oils and gases, for 
ice-making and refrigeration, the heating and draining of 
buildings, for dry kilns, hospital beds and apparatus, elec- 
tric light, railway and telegraph poles, pipe railings, for 
conduit work, etc. For many of these applications, the 
seamless variety is now utilized, however. 

For many purposes coated pipe is highly desirable. This 
may be by hot asphalt, or other liquid dip, by surface elec- 
tro-galvanizing or by the hot galvanizing method of dip- 
ping in molten zinc, by which method probably the greater 
portion of coated pipe is treated. Certain other protective 
coatings are used to a limited extent. 



CHAPTER XXI 
THE MANUFACTURE OP SEAMLESS STEEL TUBES 

It is more than likely that the popularity of the bicycle, 
which created the recent great demand for strong, light 
and perfect tubes, was largely instrumental in developing 
the seamless tube industry, which may be said to have 
"sprung up" within the last twenty-five years. Previously 
all of the iron and steel pipes or tubes obtainable were 
either of the "butt" or "lap-weld" variety with the ex- 
ception of those which were made from long pieces of metal 
by boring holes lengthwise through them. Tubes by this 
boring method are, of course, quite difficult and expensive 
to make. 

Shorter and thicker billets of steel can more easily be 
bored. When the holes have been enlarged by pushing 
larger and larger-nosed rams through them in a hydraulic 
press, they can be rolled down to size over a mandrel, just 
as lap-welded pipe is rolled, only in this case they are put 
through several times and considerably reduced in diam- 
eter. In this way some of the seamless tubes are made. 

The important starting point in all processes for seam- 
less steel tubes is the piercing operation and it is mostly 
in the method of getting the first hole through the billet 
that they differ, since the hot-rolling and the cold-drawing 
processes by which they are finished have long been known. 

One of the most important modern processes for seam- 
less tubes, the Mannesmann, is based upon the principle 

302 



MANUFACTURE OF SEAMLESS STEEL TUBES 303 

that if a white-hot round steel bar is rapidly rotated be- 
tween ' ' cross-rolls, " a longitudinal rupture which is almost 
a hole forms along its center. We may liken the motion of 
the bar in the rolls to the whirling of a lead pencil between 
the palms of our hands, except, of course, that the bar is 
kept rotating in one direction only. Though something like 
this tendency of a steel bar to open along the center through 
pressure applied at two opposite points on the outside, 
seems to have been known to forgemen, the Brothers Man- 
nesmann came upon the similar tendency under action of 
the rolls, by accident. 

They were German tool steel manufacturers. A critical 
customer wanted perfectly round and surface-polished bars 
of steel. They attempted to give his bars this perfect shape 
and smoothness by finishing them between cross-rolls which 
spun the bars rapidly around while they were slowly pass- 
ing along through the machine. The pieces were perfect 
outwardly, but, much to the steel makers ' chagrin, the cus- 
tomer reported that the quality of the steel was not as satis- 
factory as that which he previously had been receiving. 
Upon investigation it was found that this cross-rolling un- 
der pressure tended to form a small hole along the center 
of the bar with slight cracks in the metal all around it. 

Upon this happenstance discovery is based the Mannes- 
mann process for piercing the bar, which consists in push- 
ing over a piercing head such a center-weakened piece as 
it comes through the cross rolls. 

One or two modifications of the Mannesmann piercing 
method are also in use. 

The material generally used for seamless steel tubes is 
medium soft open-hearth steel of .15% to .25% carbon. It 
is received as billets which are rolled down and cut at the 
mill or they are purchased as 3" to 6" "rounds" and cut 
into such lengths as give proper amounts of steel for the 



304 NON-TECHNICAL CHATS ON IRON AND STEEL 

tubes which are to be formed. Usually the bars cut for 
tubes are from three to five feet in length. 

They are heated in a furnace and after the end has been 

dented at the 
center, they 
go into the 
rolls. 

The rolls 
seize the for- 
ward e n d of 
the bar and 
swiftly whirl 
it as it is slow- 
ly pulled in. 

A piercing head of high-speed steel at the end of a stiff 
mandrel extends between the rolls just as we saw it in the 
pipe-rolling process. As the forward end of the rapidly 




Piercing a Solid Billet bv the Mannesmann Process 




Rolling Down the Pierced Tube 



whirling white-hot steel bar pushes against this piercing 
head, the piece, weakened along its center line is pierced. 
As neither the rolls nor the piercing head can be resisted, 



MANUFACTURE OF SEAMLESS STEEL TUBES 305 

it is forced through the rolls and grinds its way over the 
piercing head with the supporting bar, the walls of the 
white-hot tube being thinned down and the piece very ma- 
terially lengthened. 

It comes out a rough tube with thick and irregular walls. 
After its removal from the rolling mill bar upon which 
another and colder piercing head is placed in readiness for 
the next tube, it goes to other rolls through which it is 
passed, first without a mandrel inside, and later, with one, 
until it has become somewhere near the desired size and 
the walls have been pulled down to the proper thickness. 
The mandrel, of course, determines the size of the interior 
of the tube, and the rolls, its outside diameter. 

Some are sold in this form as hot-finished tubes after 
having been straightened and cut to length by removal of 
the ends. 

A great deal of the seamless tubing made is given the 
cold finish, i.e., it is drawn through dies much as rods are 
drawn in the making of wire. 

For cold drawing, one end of each tube is reduced in 
size over a length of a few inches, by forging or by other 
means. This is where the "pliers" are to take hold. 

Now we can never heat steel without forming upon it a 
brittle oxide or scale which is much harder and harsher 
than the metal itself. During its sojourn in the heating 
furnace and its journey through the rolls, therefore, each 
of the tubes acquired a hard brittle surface which must 
be removed before the tube can be "drawn." The most 
practical way of removing this scale is by "pickling" the 
tube in some weak acid, usually sulphuric (oil of vitriol). 
The acid dissolves some of the scale and loosens the re- 
mainder so that it can be washed off. To neutralize any 
excess acid which clings to the tube and to aid lubrica- 
tion, it is dipped into lime-water and then dried. 



306 NON-TECHNICAL CHATS ON IRON AND STEEL 

The tube now goes to the drawing benches which are 
long steel frames along which a heavy steel draw chain 
is continuously traveling from the center toward one end. 
Anchored at the opposite end of the bench is a long bar 
upon which is fastened the mandrel or ball which is to de- 
termine the inside diameter of the tube in the drawing as 
did the mandrel between the rolls in the rolling. 

The tube to be drawn is threaded over the long rod 
which is anchored in place, and the forged-down small end 
is pushed through the "die," very firmly fastened to the 




Tube-drawing Bench 

bench near its center. The pliers take hold of the forged- 
down end of the tube with a vise-like grip, and are then 
hooked into the draw-chain. The tube is thus slowly drawn 
through the hole in the die. As these dies are of very hard 
material, either hard cast iron or hardened steel with hole 
a little smaller than outside of the tube, they compress the 
tube upon the mandrel inside and the thickness of wall is 
thus regulated, the excess metal being squeezed out so that 
the tube is very materially lengthened. Tallow or grease 
with the lime-coat lubricate the tube, a little being con- 
tinually drawn into and through the somewhat funnel- 
shaped die. 
As was the case with the "cold finishing" of plate and 



MANUFACTURE OF SEAMLESS STEEL TUBES 307 



the drawing of wire, this cold working 
increases the elastic limit and tensile 
strength of the steel. So cold-finished 
tnbes are stronger than hot-finished. 
For many purposes snch increase in 
strength is highly desirable. The ex- 
terior of the tube is also made very 
smooth and uniform in diameter by the 
drawing. 

The cold-drawing has a disadvantage, 
however. It somewhat embrittles the 
steel, as may be inferred from the in- 
crease in strength. This is not a seri- 
ous matter, however, unless the cold- 
drawing has been overdone. 

But for smaller sizes of tubing many 
drawings have to be resorted to, to re- 
duce the steel to the size required. 
Sometimes ten or even fifteen passes are 
required before the tubes reach their 
final size. In such case the tubes have to 
be annealed and repickled, limed and 
dried after each pass or two in order to 
restore to the steel its ductility. If this 
were not done the tube would eventually 
break in the die. 

The last pass is through an accurate 
"sizing" die which corrects any varia- 
tion in inside or outside diameter. 

As the pulling strain which the steel 
will stand is limited, too much of a re- 
duction in size in any single pass must 
not be attempted. 

As annealing, pickling, drying, etc. ? 



308 NON-TECHNICAL CHATS ON IRON AND STEEL 



have to be done after every pass or two, a considerable pe- 
riod of time elapses between the piercing of the billet and 
its final pass as a small tube. For economy in handling, 
tubes cannot be considered or handled singly, but must be 
treated in quantity, so this period between billet piercing 
and the final pass may be as much as two weeks, possibly 
more. 

The tubes must next be straightened. This is done in 
cross-rolls as has been mentioned under the manufacture 
of lap-welded pipe, or in various other types of machines. 

Much seamless tubing goes into automobile, bicycle, and 
various other products for which very high-grade and per- 
fect material is desirable. 
One of the many interest- 
ing applications of seamless 
tubing is its use in very 
fine sizes for hypodermic 
needles. 

Seamless tubes are easily 
bent, swaged, upset, spun or 
otherwise changed in form, 
as the material is ductile and there are nc welds to open. 

Very large tubes are not made in the way just described. 
They are rather made by "cupping" flat, round steel plates 
through a die. A cup is then in several successive drawings 
put through smaller dies, under which treatment it grows 
longer each time and gets a thinner wall until it has become 
a long tube with the one end still closed. For open ended 
tubes this and the upper, open end are cut or trimmed off. 
Cold-drawing here necessitates annealing to restore duc- 
tility just as it does elsewhere and each annealing opera- 
tion is necessarily followed by pickling for removal of the 
scale formed. 

By rapidly spinning large tubes in lathes or other ma- 




Cupping and Drawing Seamless 
Tubes from Plates 



MANUFACTURE OF SEAMLESS STEEL TUBES 309 

chines and the application of pressure with the proper tools 
and lubrication, the walls of the tubes may be deformed. In 
this way the ends may be expanded, made smaller, or com- 
pletely closed. By such "spinning" operations large tubes 
are made into articles of various shapes. 

By this same "cupping" or hydraulic drawing of flat, 
well lubricated sheets of soft steel, seamless high-pressure 
gas cylinders, steel drums, barrels, and the like are made. 



CHAPTER XXII 

TRANSFORMATIONS AND STRUCTURES OF 
THE STEELS 

It was "Ali Baba" who is quoted as saying, "Those who 
do not know how to take the Philistine, better hadn't!" or 
words to that effect. 

Now through these chapters we have attempted to discuss 
in an entirely non-technical manner the subjects presented. 
On this account we were compelled to forego discussion of 
many things which are highly important and interesting 
but which are more or less difficult of explanation without 
the use of scientific terms and theories. One such has been 
the "mechanism" of the hardening of steel and its opposite, 
its softening by annealing. For those who may desire to 
get a glimpse into this "wonderland" it is hardly fair to 
refrain from brief discussion of the subject just because it 
is technical and difficult and so may prove to be tedious to 
some who have little reason to be interested. 

It seems desirable, therefore, to impose this more tech- 
nical chapter or two that the subject of the real metallurgy 
of iron and the steels may at least be "hinted at." We say 
"hinted at" advisedly for it is a long, long story, and, even 
now, after a great many years of serious study no one has 
yet read it to the end. We are not saying this in a dis- 
couraging way, however, for there seems little reason to 
doubt that the multitude of facts which have been dis- 
closed through the tireless experiments and the study of 

310 



TRANSFORMATIONS AND STRUCTURES OF STEELS 311 

hundreds of investigators have put us well on our way to 
the solution of this one of Nature's great problems. 

To those, however, who are not interested in the known 
details of "how" and "why" hardening and softening of 
steel is possible and why hardening of pure iron and mild 
steels does not and cannot take place, we must say as would 
"Ali Baba": — "Those who do not care to study it better 
hadn't." Anyway, the study of this rather intricate sub- 
ject is conducive of "headaches," and perhaps it is not ex- 
tremely important when viewed from the non-technical 
standpoint of these articles. 

We have several times referred to the debt which civiliza- 
tion owes to iron and steel structural materials, machinery 
and tools and particularly to those tools which have hard- 
ened cutting edges. Almost every one knows that hardened 
cutting edges are imparted to tools by sudden cooling in 
water or oil from a good red heat. Probably most of us, 
too, know that the blacksmith can again soften such tools by 
reheating to the same red heat and allowing them to cool 
slowly. This he calls annealing. In this softened or an- 
nealed condition a piece can readily be sawed or filed, while 
in its hardened state a saw or file produces no result 
upon it. 

Now what are the facts, meaning and the cause of this 
dual life of the alloy, steel, without which we would be so 
greatly handicapped. 

To be better prepared to understand the answer, let us 
consider three or four accompanying and closely allied 
phenomena which close observation of the habits of steel 
has disclosed. 

The "'Point of Recalescence" 

If we drill a hole in a small piece of carbon tool steel 
which we are about to put into the heating furnace, and if 



312 NON-TECHNICAL CHATS ON IRON AND STEEL 

into this hole we insert the bare tip of an electric pyrom- 
eter, this heat-measuring instrument will indicate at all 
times the rising temperature of the piece of steel as it 
heats in the red-hot muffle or chamber of the furnace. 

As we watch the piece grow red, the pyrometer registers 
900°, 1000°, 1100°, 1200° F. ,— gradually and uniformly indi- 
cating higher and higher temperatures. 

But lo! Something must be wrong! The pyrometer 




Apparatus for Determining the Critical Points of Steel 



needle does not now move forward but is standing still. 
Though we know that in that hot furnace the piece must be 
absorbing heat at the same rate as before, yet the pyrometer 
needle does not budge ! 

But, as our wonderment grows and we are still undecided 
as to the meaning, the needle again begins to advance and 
continues again regularly and uniformly to higher and 
higher temperatures as though it had never taken the va- 
cation. 



TRANSFORMATIONS AND STRUCTURES OF STEELS 313 

With the piece now at a white heat, we have proceeded 
far enough with the heating. 

Turning off the electric current from the furnace and al- 
lowing it to cool we again watch the pyrometer needle as 
the temperature of the piece in the cooling furnace gradu- 
ally falls. Lower, lower, lower swings the needle, always 
at a rate approximately uniform. 

But again it suddenly stops and remains immovable, or 
perhaps even rises slightly, for a period of several sec- 
onds, after which it resumes its uniformly-timed downward 
course as though nothing had happened. 

Yes, these pauses of the needle occurred at very nearly 
the same marking on the pyrometer dial, but not at exactly 
the same ones. Going up it was at 1350° F., and on the 
downward way it was at 1250° F. And you are correct in 
surmizing that these two points are closely related. They 
are parts of the same, if we may so speak, and, in reality 
they represent one point which is located about halfway 
between them, the divergence resulting from what is known 
as "hysteresis" or "lag," which means, of course, a "be- 
ing-behind-hand" or tardiness. 

For the present we may say that all carbon steels have 
this "critical" range as shown by such pauses of the py- 
rometer needle during heating or cooling of the steel. 

Now as the piece is most certainly continuing to absorb 
heat in the furnace as it grows hotter and is losing it uni- 
formly to the air as the furnace cools, we have no alterna- 
tive but to judge that the pause of the needle on its upward 
way was caused by some internal affair of the piece of steel 
itself, for which, at just that stage of its journey, it re- 
quired and used for its purpose (which was other than mak- 
ing itself hotter), the heat furnished it by the furnace; and, 
that on the downward journey, at just that same point, it 
gave out again that same heat. It must have been the set- 



314 NON-TECHNICAL CHATS ON IRON AND STEEL 

ting free of this imprisoned heat, if we may so term it, 
which kept the piece for those few moments from cooling 
at the usual rate. Indeed, had we conducted our experi- 
ment in a rather dark room and observed the piece closely 
we would have noticed that during the pause of the pyrom- 
eter the piece of steel did brighten or glow somewhat, 
showing that it had extra heat from some hidden source. 
Because of this "self-heating" of the steel as shown by the 
pyrometer and the brightening, the temperature at which 
the phenomenon occurs has been named the "point of re- 
calescence," which means the point at which it spontane- 
ously becomes hotter. 

Loss of Magnetism 

Now another curious thing took place had we but no- 
ticed it. 

We all know that iron and steel are our most magnetic 
materials. From childhood we have seen pins, needles, 
steel pens, and various other steel or iron objects jump to 
a magnet held near them. 

What, now, when we find that our piece of steel in the 
furnace when at a red or higher heat is entirely unrespon- 
sive or dead to the attraction of a strong magnet*? 

Strange! Do you suppose that our magnet has lost its 
power? 

Let us see. 

Suppose that every minute or so, while watching the 
pyrometer needle go slowly down again after turning off 
the heat, we put the magnet to the steel. 

Continually lower comes the temperature of the piece — 
1500°, 1400°, 1375°, 1350°, 1325°, 1300°, 1275° F.,— andlo! 
the piece jumps, and from this all the way down to cold it 
responds to the attraction of our magnet. Just to make sure 
that we are not "seeing things," we again start our fur- 



TRANSFORMATIONS AND STRUCTURES OF STEELS 315 

nace, and, as the steel heats, we test it with the magnet. 

So far there is no doubt about its being magnetic ! 

At 900° F., the pieces begins to show dark red, at 1000°, 
1100°, 1150°, 1200°, 1250°, stronger and stronger red. At 
all of these temperatures the steel is attracted. So it is at 
1275° and at 1300° F. 

But just as we are thinking that we must have been 
mistaken before, we find that again the steel is suddenly 
"dead" to the pull of the magnet! 

And at what temperature? The pyrometer indicates 
1320° F. But was not this the same or very nearly the 
same reading at which the pyrometer needle paused on the 
way up, and do you not remember that it was only a little 
below 1250° F. that it paused on the way down, and the dis- 
agreement of the two temperatures we ascribed to "lag"? 

No, we made no mistake. Steel loses all of its magnetic 
properties at the "critical range" and has none above it. 

Dilatation and Conductivity 

Certain other great changes, too, occur here. 

We know that most materials expand uniformly upon 
heating and contract as they cool. Steel is no exception, 
but at the critical range on heating it becomes fickle and 
for a short space contracts instead of continuing its uni- 
form expansion. Conversely, during cooling, it ceases its 
uniform contraction and suddenly dilates or expands for a 
short period when it reaches the critical range, after which 
aberration it again resumes its old habit of uniform con- 
traction as the temperature falls. 

Just so with its electrical conductivity. At the critical 
range the electrical conductivity suddenly decreases abnor- 
mally as the piece gets hotter and as abnormally increases 
as the steel cools through the critical range on the return 
trip. 



316 NON-TECHNICAL CHATS ON IRON AND STEEL 



2\t9oo 
<V 75 
i SO 

% » 
> if 



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b W 

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0, /Joo 
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Stars trace Weat/'ng Curve. 
Po/s ■• Cooling 



There are certain other happenings at or near this par- 
ticular temperature but we will not consider them here. 
Manifestly all of this has a deep meaning, 

Recalescence Indicates the Hardening Point 

You remember that we said the divergence between the 

going up and the coming down pauses of the pyrometer 

_ . _ needle was due to 

S/ee/ or abauf.9/t, Carbon. . t i a 

tardiness or lag/ 
Among humans ha- 
bitual tardiness is 
not considered a de- 
sirable trait, but it is 
undoubtedly through 
this very lag or tar- 
diness that steel be- 
comes so serviceable 
to us. 

This lag is peculiar 
in that it grows less 
the more slowly we 
heat or cool the steel, 
and, if the heating or 
cooling is done slow- 
ly enough, the lag 
disappears almost 
entirely, i.e., the 
pause of the pyrometer needle occurs at the same tempera- 
ture on the upward as on the downward way. Conversely, 
the disagreement or split grows or widens the faster the 
temperature is raised or lowered. 
Here is the vital point. 

By extremely sudden cooling, such as quenching in water, 
the lag becomes so great that it never catches up at all and 




j£w 



Time in Seconds 

Heating and Cooling Curves of Steel with 
.9 Per Cent op Carbon 



TRANSFORMATIONS AND STRUCTURES OF STEELS 317 

any structure with its consequent properties which was 
brought about in the steel by the higher temperature is 
thus frozen or fixed and made to "persist" after the steel 
has become cold. 

It is just at this point, the "point of recalescence," that 
steel changes from its soft and malleable, to its extremely 
hard and brittle 
condition. If it is 
quenched from 
temperatures 
above this point, it 
is extremely hard, 
if from tempera- 
tures below it, even 
those only a little 
below, it is soft 
and ductile. It is 
from just a little 
above this point, 
then, usually be- 
tween 1350° F., 
and 1500° F,, that 
the blacksmith 
hardens his tools 

, , . Heating and Cooling Curves of Steel with .46 

by plunging them per cent of carbon 

into cold water. 









Stars trace Heating Curve. 


1 


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r ime in 


Seconds 



Steels of Other Composition 

Now it should be noted particularly that the specimen 
with which we have been experimenting is a tool steel of 
.90 % carbon or thereabouts. This is important, for, while 
all of the carbon steels show this same critical temperature, 
at which occurs the point of recalescence, those contain- 
ing from .45% to about .85% carbon have another point 



318 NON-TECHNICAL CHATS ON IRON AND STEEL 

somewhat higher on the temperature scale, and steels which 
contain from .10% to .45% of carbon have two others, or 
three points in all. Further, steels having less than .10% 
of carbon and iron with no carbon at all have the two upper 
points but no point at 1290° F. This lower one has dis- 
appeared. 

All of this means that if instead of a piece of .90% car- 
bon steel we had used one having .60% of carbon, say, we 
would have found two different critical ranges or points at 
which the pyrometer paused, the one at 1290° F., and an- 
other when we got to 1360° F. Had the steel been one 
containing .30% carbon we would have discovered pauses 
at three different points, viz., at 1290° F., at 1395° F., and 
at 1480° F. With very low carbon steel or with wrought 
iron, the pyrometer would have registered two pauses, one 
at about 1395° F., and the other at 1650° F. 

When records are carefully kept of the time which is re- 
quired for the temperature to rise or lower over each and 
every twenty-five degree period, say, on the upward and 
downward way, and these are "plotted," what are called 
"heating" and "cooling" curves can be drawn through the 
stars and dots so set down and these form a record of the 
behavior of the pyrometer needle at each temperature along 
the scale. Two illustrations of such curves are shown.* 

Now if on properly spaced, dotted, vertical lines, which 
we will let represent these various alloys, we mark points 
number three, two and one as shown by our "cooling" 
curves, calling the topmost point three, it is readily seen 
that the points are related. The lines and the alloys which 
they represent are, 

(a) The wrought iron, 

(b) .15% carbon steel, 

* Special apparatus is now obtainable for determination of critical points, 
heating and cooling curves. 



Temp 
rQhr ( aj 
/7O0'r 



Critical Points of Pure Iron and the Stee/s 
i*L_ _ J0_ . j*l ._ JfJ'- -(M &L_ -C&L 



I600 



1500' 



/400", 



■30a 




/2od\ l j i J i i I l 

(a) (/■) (c) (d) & ft) m (A.) (I) 

0% .15%, .30% 45% .60% .75% .90% lOSZ *' 20 7< 

Carbon in fh® A/ toy. 

Critical Point Diagram of Pure Iron and the Steels 



319 



320 NON-TECHNICAL CHATS ON IRON AND STEEL 

(c) .30% carbon steel, 

(d) .45% carbon steel, 

(e) .60% carbon steel, 

(f) .75% carbon steel, and 

(g) the steel with .90% carbon. 

Of course many more cooling curves, especially of steels 
with other percentages of carbon would be desirable, but we 
have enough that we are safe in sketching the horizontal 
and oblique lines, Ar x , Ar 2 , Ar 3 , Ar 3 . 2 and Ar 3 . 2 .i through 
the points which we have arranged. 

For convenience, metallurgists everywhere mark these 
points Ar 1? Ar 2 and Ar 3 , the first being the lower, and Ar 3 
the upper one. Arcm represents an upper point found in 
steels having more than .9% of carbon. The letter "r" is 
derived from the French word, "refroidissement," mean- 
ing "cooling." The corresponding points disclosed dur- 
ing heating are marked Ac a , Ac 2 , Ac 3 . 2 .i, etc., from the 
word, "chauffage" meaning "heating." The "A" appar- 
ently "just happened." Before the upper critical points 
were known it had been used by TschernofT to designate the 
temperature at which steels harden. 

But it must not be supposed that the skeleton which we 
have constructed can be fully accepted as true until it has 
been checked and rechecked hundreds and hundreds of 
times by other investigators. A great many have worked 
upon these critical points and upon the "freezing point" 
curves of the various alloys. It was of course impossible 
for all of them to make their determinations in just the 
same manner and with exactly the same materials. Exami- 
nation of their work and consideration of the results which 
they obtained show some discrepancies as might be ex- 
pected, largely probably because of difference in purity of 
the materials tested, every impurity such as manganese, 
nickel, silicon, sulphur, phosphorus, etc., modifying more 



TRANSFORMATIONS AND STRUCTURES OF STEELS 321 

or less the results obtained. As we discovered, speed of 
heating and cooling also modify the results. When we con- 
sider the difficulties which attend the making of determina- 
tions on metals and alloys at high temperatures, the won- 
der is that there is such close agreement. From these 
standpoints the differences which exist in the published re- 
sults seem quite small. 

It was but twenty years ago that the first outline was 
drawn and the whole ''fusibility" or "equilibrium dia- 
gram" of the iron-carbon alloys given in the next chapter 
has practically been developed within this time. But over 
this period of twenty or so years the points upon which these 
lines Ar x , Ar 2 , Ar 3 , Ar 3 . 2 and Ar 3.3.x are based have been 
checked many times and they are now well substantiated. 
These lines form but a small part of the complete "iron- 
carbon diagram." 

The Meaning of the Points 

You remember that wrought iron and steels having less 
than .10% carbon showed no point Ar x , and that in all other 
steels this point becomes stronger as they contain higher 
and higher carbon. There is little doubt that the point Ar x 
exists or results from and because of the carbon of the 
alloy. In wrought iron there is no carbon, hence there is no 
point Ar x . If the extremely low carbon steels have an Ar x 
it is so weak that it cannot be detected. 

Had we tested the .45% carbon steel for magnetic prop- 
erties we would have found that it lost magnetism at about 
1395° F., instead of at 1290° F., at which temperature the 
.90% steel became non-magnetic. The point Ar 2 , then, 
shows the temperature at which loss or gain of magnetism 
occurs. The electrical conductivity change comes at neither 
of these points, Ar x , nor Ar 2 , but at Ar 3 . 

However, with increase of carbon the line Ar 3 , which was 



322 NON-TECHNICAL CHATS ON IRON AND STEEL 

drawn through the points, Ar 3 , rapidly descends. At about 
.45% or .50% carbon content, this line Ar.,, representing 
the changes in conductivity, joins line Ar 2 . Hence in steels 
having .45% carbon or more, there is a common point, or 
one which in reality is made up of both points. At this 
common point the phenomena peculiar to each of the points 
occur. 

This common line, now called Ar 3 . 2 , itself lowers with fur- 
ther increase of carbon until, in steels of around .90% car- 
bon, there is but the single point Ar 3 . 2 . 3 , and the phenomena 
corresponding to all three of the points occur at this one 
point at 1290° F., as we found in our experiments. 

As points Ar 2 and Ar 3 occur in carbonless iron, they can- 
not result in any way from carbon but must have to do with 
the iron itself. From their experiences with other ma- 
terials, chemists and physicists are well acquainted with 
such evolutions of heat as occur at Ar 2 and at Ar 3 . These 
heat absorptions and evolutions, with the sudden dilatation, 
gain in conductivity, etc., indicate that some internal change 
or reorganization takes place in the iron itself. 

Such changes seem to indicate what are known as "allo- 
tropic" modifications. More familiar examples of allo- 
tropic forms of materials may be mentioned. Phosphorus, 
for example, may exist, either as the "yellow" variety 
which is poisonous and so inflammable that it must be kept 
constantly under water, or as the "red" variety which is 
non-poisonous and non-inflammable. Too, there is carbon, 
which may exist in any one of several forms such as amor- 
phous carbon (soot), graphite, and the diamond. It is be- 
lieved that iron, itself, exists in three allotropic states. 
These have been named "alpha," "beta" and "gamma" 
iron. We do not need to go into this part of the great sub- 
ject except to state that at ordinary temperatures and up 
to Ar 2 , we have alpha iron, between Ar 2 and Ar 3 , beta iron, 



TRANSFORMATIONS AND STRUCTURES OF STEELS 323 

and above Ar :5 , gamma iron. Both beta and gamma iron 
are non-magnetic, while alpha iron is strongly magnetic. 
In cooling through Ar ; >, i.e., from gamma to beta iron, some 
rearrangement of its molecules produces the dilatation or 
expansion and the change in conductivity which was noted 
above. 

From the fact that by chemical analysis any certain steel 
must have the same composition in its hardened that it has 
in its unhardened condition, it will readily be seen how 
futile it would be to expect chemical analysis to give us 
complete information regarding it. Too, tensile strength 
and the other usual physical tests can hardly tell us all that 
we wish to know. Microscopic analysis or metallography, 
however, shows us internal structure of properly prepared 
pieces of either the hardened or unhardened alloy that we 
may see the actual condition or grouping of the constit- 
uents. The view points given by all three of these methods, 
chemical, physical and metallographical, are, of course, 
much better than any one or two alone. 

The Structures of Quenched and Unquenched Steel 

We saw that the lag or tardiness is greater the more 
rapid the cooling. Along with this very great lag which 
is brought about by very rapid cooling comes increasing- 
slowness, i.e., less ability to catch up, as the temperature 
is lowered. Hence quenching produces such a wide lag and 
so slows the changes which should take place that they do 
not take place at all, i.e., the structure which the piece had 
at the higher temperatures cannot change but is set or fas- 
tened by the quickness of the cooling. 

Though no degree of suddenness is sufficient to set com- 
pletely the structure existing at very high temperatures, 
for our present purposes we can say that by quenching in 
cold water we can freeze or fix any structure. Then after 



324 NON-TECHNICAL CHATS ON IRON AND STEEL 



we have quenched a piece of steel, it will have when cold, 
the structure which corresponded with or resulted from 
the temperature which it had at the moment before the 
quenching. 

If so, the microscope should give us aid. 

By breaking 
off pieces of a 
quenched piece and 
very carefully and 
slowly grinding 
and polishing with- 
out heating a sur- 
face which was an 
interior part we 
find after etching 
that we can actu- 
ally see the kind of 
structure which 
corresponded with 
the temperature 
from which 
the piece was 
quenched. 

Photomi- 
crograph No. 80 
shows the appearance of a piece of hardened carbon steel. 
Note the needle-like structure under the microscope at mag- 
nification of 400 diameters. This structure is character- 
istic. 

The constituent having this needle-like appearance has 
been named "martensite" in memory of a distinguished 
European metallurgist, A. Martens. It is supposed to be 
"beta" iron, much the hardest allotropic variety of iron, 
and to hold in solution the carbon of the alloy, either as 




s+ee/ 



Illumination of the Sample under the 
Microscope 



TRANSFORMATIONS AND STRUCTURES OF STEELS 325 



carbon alone or as the extremely hard chemical compound, 
iron carbide, Fe 3 C. 

Martensite, then, is the extremely hard structure, neces- 
sarily containing considerable carbon or iron carbide in 
solution which gives to our carbon tool steels their hardness 
and great usefulness. 

Unhardened steels never look like this. Their appear- 
ance is shown in photomicrographs Nos. 3b, 5, 22 and 24a. 

In unhardened 
steels having less than 
.90% of carbon we find 
two constituents. 

"Ferrite" is the 
name which has been 
given to one, the soft 
and ductile constitu- 
ent, pure iron. With 
ordinary etching the 
ferrite usually shows 
as light-colored 
or white grains 
bounded by black 
lines, which, if the patch is large enough, give a fish-net 
appearance. It is soft and ductile like copper, for pure 
iron and pure copper are not so greatly different in mal- 
leability and ductility as one might suppose. 

The darker and more or less triangular patches at the 
corners of the ferrite grains are "pearlite," a name origi- 
nating because of their "pearly" appearance under the 
microscope. How this pearly appearance comes about will 
be readily understood from photomicrograph No. 23e which 
was taken at a magnification of 400 diameters. It is seen 
that it results from alternate black and white layers. 

Again we must give up the idea of any finality in the 




No. 80. Martensite, the Constituent op 

Hardened Steel 

(Magnification 1,00 Diameters) 



326 NON-TECHNICAL CHATS ON IRON AND STEEL 



things we learn or think we have learned. We just learned, 
for instance, that ferrite usually was light or white in color. 
Well, in pearlite, as shown in photomicrograph No. 23e, 
every other plate is of ferrite but they are not the white 
but the black ones. 

You may not have understood before that color as shown 
under the metallographic microscope depends not so much 
upon actual color of the material itself as upon its ability 
to reflect light. For metallographic observations it is nec- 
essary to have very strong illumination. Usually the pow- 
erful beam from an 
electric arc is concen- 
trated by means of 
condensing lenses 
upon a thin disc of 
glass called an oblique 
reflector which directs 
the beam upon the pol- 
ished and etched speci- 
men beneath the objec- 
tive of the microscope. 
Often a prism is used. 
The rays of light re- 
turning from this highly illuminated "field" under obser- 
vation return up through the tube and eye piece of the mi- 
croscope and can be focused upon a small screen convenient 
for observation or upon the ground glass of the attached 
camera by means of which the pictures are taken. Unless 
the surface of the specimen being examined is perfectly 
plain and level, not all of the vertical rays thrown down 
upon it will be reflected back up through the tube and eye 
piece. Those portions of the field which are absolutely at 
right angles to the vertical rays appear at the eye piece 
or upon the screen as white or light-colored portions, while 




No. 23e. 



Pearlite at Magnification of 400 
Diameters 



TRANSFORMATIONS AND STRUCTURES OF STEELS 327 

those which, during the polishing or etching have been dug 
or eaten away reflect the light imperfectly or in directions 
other than up the tube of the microscope, wherefore such 
portions show as darker or black sections. 

The pearlite, then, is made up of little plates of soft fer- 
rite alternating with others of a very much harder constit- 
uent. The harder plates are much less affected during pol- 
ishing and etching than are those of the softer ferrite, hence 
they stand out in relief and reflect abundant rays of light, 
whereas the "dug-out" ferrite plates reflect the light im- 
perfectly or not at all and therefore appear as dark lines. 

These white, hard plates of the pearlite contain all of the 
carbon of the low carbon alloys. They are this other con- 
stituent, "cementite," so named because it was first dis- 
covered in steel made by the "cementation" process. It 
is a very hard and brittle substance, hard enough to scratch 
glass. It is the chemical compound (Fe 3 C), unvarying in 
composition as chemical compounds always are. It con- 
sists of just three atoms of iron (93.4% by weight) and one 
of carbon (6.6%). 

Pearlite, therefore, is a sort of mechanical mixture of 
two separate constituents, ferrite or pure iron, and this 
chemical compound, carbide of iron, which is called cement- 
ite. Pearlite is common to all unhardened steels whether 
of low, medium or high carbon content and may be con- 
sidered characteristic. 

That we may understand clearly the structures of the 
annealed steels, let us start with pure iron and gradually 
change it into higher and higher carbon steels by gradual 
addition of carbon. Pages 328 and 329 show such a series. 

Photomicrograph No. 99b is open-hearth iron which is 
entirely made up of free ferrite. In No. 3b there is con- 
siderable pearlite, here appearing black, though the sam- 
ple of steel yet contains but .10% of carbon. In No. 5, 



328 NON-TECHNICAL CHATS ON IRON AND STEEL 







■<**>■* 












No. 99b. Carbonless Iron 



No. 3b. Steel with .1 Per Cent 
Carbon 




No. 5. Steel with .3 Per Cent No. 22c. Steel with .5 Per Cent 

Carbon Carbon 

(Magnification 60 Diameters.) 

which is of a steel containing .30% of carbon, we have more 
pearlite and in No. 22c with .50% carbon we have yet more. 
Manifestly at this rate the comparative pearlite areas are 
growing so that there will soon be room for no ferrite at 
all. In No. 23g this has occurred. This, the photomicro- 
graph of a steel containing .86% of carbon is one of the 
steels in which we found that the point of recalescence, loss 
of magnetism, decrease in electrical conductivity and rate 
of expansion take place all at the one point. 

Now as we go still farther on up in percentage of car- 
bon content, i.e. (beyond .86%, we have a white constituent 



TRANSFORMATIONS AND STRUCTURES OF STEELS 329 




No. 23s 



Steel with .9 Per Cent 
Carbon 



No. 24a. 



Steel with 1.25 Pee Cent 
Carbon 



Y» ' **£* - : "f / ■ ■ ^ ' ' '' ■ ■" - ' '-■' *" '* •■ 


t* % 




- , :- "• 

JssJS 


" ... . J* 




^iSSspySf^SkSs 



No. 36b. Steel with 2 Per Cent No. 109. White Cast Iron with 3 Per 
Carbon Cent Carbon 

{Magnification GO Diameters.) 

beginning to appear as cell walls around the grains of the 
pearlite and this increases with increase of carbon until, 
with alloys having carbon around 3%, we have a propor- 
tionately small amount of pearlite while the white areas 
have so increased that it appears that the more or less 
round patches of pearlite float in a lake of white. This 
white which appears first as cell walls, and later in greater 
and greater quantity is free cementite. 

Such are illustrated in photomicrographs Nos. 24a, 36b 
and 109 which contain 1.25%, 1.98% and 3.00% of carbon 
respectively. While steels with the typical white, free fer- 



330 NON-TECHNICAL CHATS ON IRON AND STEEL 



rite areas are so soft that a needle-point will plow furrows 
across them, those with over 1.25%. of carbon have such 
excess of free cementite that they are very hard to scratch 
and too brittle to use except for special purposes. 

So during ordinary cooling from the molten alloy or 
the slower cooling of the steel during the annealing process, 
the martensitic structure breaks down at the recalescent 

temperature into 
pearlite and f errite 
(soft iron) if the car- 
bon content of t h e 
steel is lower than 
about .90%, or pearl- 
ite and the other and 
very hard constitu- 
ent, "cementite," if 
the steel has more 
than .90%o of carbon. 
If the carbon content 
happens to be just 
.90%), or thereabouts, 
there is exactly suf- 
ficient pearlite to 
make up the total 
area of the field shown under the microscope. 

Another constituent which is of great interest scientifi- 
cally, though not at all commercially, is "austenite." By 
quenching very high carbon steels from a very high tem- 
perature very suddenly and completely, we can fasten the 
"austenite" structure, which exists only at temperatures 
higher than martensite, i.e., austenite is our gamma iron 
with the carbon of the alloy in solid solution, perhaps as 
iron carbide, while martensite is thought to be the beta iron 
solid solution, perhaps with some gamma iron mixed with it. 




Austenite (White) and Martensite (Dark) 
Magnified 1,000 Times Their Actual Size 



TRANSFORMATIONS AND STRUCTURES OF STEELS 331 



While ordinary quenching fastens structures pretty well, 
it is not usually quick enough to prevent the austenite from 
sliding along down into martensite. However, carbon dis- 
courages such slipping, so, with high carbon to act as a 
brake, we can fasten some of it by chilling very suddenly 
and completely from a very high temperature. Steels with 
1.5% of carbon and temperatures of 2000° F., or over, are 
usually necessary to accomplish it. 

However, austenite, after we get it, is not as hard as 
martensite and we have little use for it commercially. As 
was stated before, 
martensite is the use- 
ful and proper struc- 
ture for carbon steel 
tools. 




No. 73. Annealed Steel has Fine Grain 
(Magnification 70 Diameters) 



Tempering or Drawing 

"Tempering" is 
done to relieve the in- 
tense brittleness of 
steel after quenching 
to martensite. While 
we dislike to sacrifice 
any of the hardness, it pays to temper or "toughen" the 
steel, as the toolmaker calls it, by reheating it to some- 
where between 400° and 570° F. 

The higher the temperature, the freer and quicker is 
the change from one structure to another, as, for instance, 
the austenite to martensite. At the low drawing tempera- 
tures the changes from martensite to the pearlitic struc- 
ture may be said to just creep along. A second quenching 
then fastens it at the new structure which gives a trifle 
less hard but a tougher steel. As you would guess, the 
microscope shows on these what we may term a "trans- 



332 NON-TECHNICAL CHATS ON IRON AND STEEL 

ition" or "breaking-down" appearance and structures not 
at all definite. These, of course, give to the steels the various 
degrees of hardness and brittleness and other qualities 
which are so desirable from the practical standpoint. The 
production of these fine shades of temper by the practical 
tool maker or blacksmith may almost be considered a 
fine art. 

How and Why Do the Steels Harden? 

Now, from all of these facts, what, shall we say, is the 
cause of the hardening of steel? 

The explanation most generally accepted seems to be, 
that, of the three allotropic forms of iron the gamma and 
beta varieties are very much harder than alpha iron, which 
is the one which we have in annealed steel at ordinary tem- 
peratures, and, of the two, the beta is harder than the 
gamma variety. It is thought also, that carbon, perhaps 
as carbide of iron, is held in solution in gamma or beta 
iron after the quenching, and increases the hardness pro- 
portionately with increase of the carbon content of the steel. 
While this carbon or iron-carbide solid solution may and 
probably does itself confer additional hardness to the steel, 
its main function is to retard or slow down the change from 
gamma into beta and alpha iron, which change in carbon- 
less iron and low-carbon steels is so insistent and extremely 
rapid that not even the most severe quenching, as in ice- 
water or liquid air, can prevent or stop it. Not only do 
we fail to get austenite, which is gamma iron, until we 
get 1% or more of carbon present and quench from very 
high to very low temperatures, but we cannot even stop 
the transition at beta iron, the next lower allotropic va- 
riety until we have at least .30% of carbon, and, for 
serviceable hardening fully .60% of carbon in the steel. 

Fortunately for us, this beta form of iron is the one we 



TRANSFORMATIONS AND STRUCTURES OF STEELS 333 



want, for it is harder and more useful than the gamma 
form. 

Our most serviceable constituent, martensite, then, is a 
solid solution of carbon or iron carbide in beta iron. It is 
magnetic but this probably results from its containing some 
alpha iron through incomplete stoppage of the change by 
the quenching. 

As has been stated, "tempering," which means careful 
reheating to 400° P., 500° F., or 600° F., allows the slight 
"slipping" of enough 
of the beta solution, 
always eager at tem- 
peratures below the 
point of recalescence 
to return to alpha con- 
dition, to relieve 
the excessive brittle- 
ness of the hardened 
steel. 

Annealing is the 
complete release 
of beta iron and the 
"trapped" carbon 
which allows of their return to the normal condition of 
pearlite with alpha iron. To accomplish this, the hardened 
steel has to be heated above its point of recalescence and 
cooled more or less slowly. Different speeds of cooling 
give different grain size, structures and physical prop- 
erties. 

This explanation of hardening, which is known as the 
"allotropic" theory, is not universally accepted, conclu- 
sive evidence being lacking at more than one point. 

It must be stated also that some who hold the "allo- 
tropic theory" of hardening doubt the existence of beta 




No. 72. The "Sorbite" Grain Is Produced bv 
Cooling in a Blast of Air after Annealing. 
It Gives Good Wearing Properties 
(Magnification 70 Diameters) 



334 NON-TECHNICAL CHATS ON IRON AND STEEL 

iron. These contend that the so-called beta iron and mar- 
tensite are only decomposition or transition forms of 
gamma iron and austenite. 

Two 01 three other theories have been more or less 
strongly advocated but these also suffer from lack of evi- 
dence. The one which perhaps ranks next in number of 
advocates is the ''carbon theory." Its supporters contend 
that by quenching, alpha iron is made to hold carbon or 
iron carbide in solid solution and that it is this solution of 
carbon or carbide which gives to the steel hardness in pro- 
portion to its carbon content. Others hold that the great 
density or strain under which quenched steel exists ac- 
counts for the hardness. 

Like many other great problems of the universe this one 
is not yet conclusively or satisfactorily solved, so reluct- 
antly does Nature yield her secrets. But while it may not 
have explained all of the "whys" and "wherefores, " the 
work which investigators have done has brought about 
great improvement in methods of manufacture and quality 
of the alloys which are making our civilization greater and 
this Age more wonderful. 



CHAPTEE XXIII 

THE EQUILIBRIUM DIAGRAM OF THE IRON- 
CARBON ALLOYS 

It was a great day for metallurgy when it was discovered 
that molten mixtures were governed by the same natural 
laws which govern our ordinary liquid solutions. Prob- 
ably it was because most metallic alloys are solid at ordi- 
nary temperatures and liquid only at very high ones that 
for so long a time we failed to suspect their similarity. 

If a sensitive pyrometer is inserted into an ordinary solu- 
tion or a molten alloy which is being gradually cooled, it 
indicates the first instant that solidification (freezing) be- 
gins as well as the termination of the freezing period. Un- 
like the freezing of water or a pure metal, complete solidi- 
fication ordinarily does not take place at a definite single 
temperature but over a greater or lesser range of tempera- 
ture. By taking such upper and lower freezing-point meas- 
urements for many different percentage compositions of a 
binary (two metal) alloy, for instance, curves can be plotted 
which show accurately the habits of any and all of the pos- 
sible combinations (i.e., alloys) of those two metals. 

Such are called "freezing-point" curves, and, as we shall 
see later on, a study of them will give us much valuable 
and interesting information. 

Such curves have been constructed for a great many alloys 
since the discovery of the analogy between their behavior 
and that of aqueous solutions led us to study alloys after 

335 



336 NON-TECHNICAL CHATS ON IRON AND STEEL 

the manner which physical chemists found so satisfactory 
for the study of ordinary solutions. Since the study of 
binary or two metal alloys is often very difficult, it can be 
readily understood why the determination and interpreta- 
tion of the curves of alloys which contain three, four or 

Freezmg-Poini Diagram of Iron -Carbon AHous 




The Freezing-Point Curves of the Iron-Carbon Alloys 



more metals is a very much more serious matter. Much of 
it has to be done by methods which are long and tedious, 
such as quenching and microscopic study of innumerable 
specimens taken during the freezing and subsequent cool- 
ing of various alloys of each series. The value of the re- 
sults depends upon the skill, devotion and clear sighted- 
ness of those who carry out the work. 



EQUILIBRIUM DIAGRAM OF IRON-CARBON ALLOYS 337 

The "freezing-point" and "decomposition" curves of the 
iron-carbon series of alloys have been brought to their pres- 
ent stage of development after something like twenty years 
of labor by investigators in many lands. If we look at the 
diagram on page 345, we note at once that the curves are 
quite complicated. Even yet they are not complete for all 
percentage combinations of iron and carbon, and those who 
have given the most time and study to the subject have not 
yet been able to interpret with entire satisfaction to all 
concerned all of the discoveries so far made. 

Without endeavoring to take up in detail the technique 
of the manner of their production, which would be unprof- 
itable for us without a great deal more of preliminary study 
than we have time and space to give, we will at once ex- 
amine the freezing curves of the iron-carbon alloys as now 
developed. The works named on page 354 as references 
for Chapters XXII and XXIII may be consulted for the 
various types and methods of construction and for explana- 
tion of freezing curves by those who desire to study them. 

Referring to the freezing-point diagram on page 336, the 
upper or broad V-shaped line, ABC, indicates the tempera- 
tures at which the alloys of various percentages of iron 
and carbon begin to freeze, and the lower one, AED, the 
temperatures at which the freezing of these alloys ends. 
From the diagram it is readily seen that pure iron (100%), 
has a very high freezing point and solidifies at once. Iron 
which contains about 2% of carbon begins to freeze at a 
much lower temperature and has a long period of solidifi- 
cation, while iron with 4.3% of carbon has the lowest freez- 
ing-point of the series with an extremely short solidifica- 
tion period or range. 

Since we have been unable to go sufficiently into the 
methods and technique of freezing-curve construction to 
be able to understand their general classification, we must 



338 NON-TECHNICAL CHATS ON IRON AND STEEL 

accept the statement that the curve of the iron-carbon se- 
ries is really a double one. The part of it that lies to the 
left of the dividing line UV of the diagram on page 336, is 
of the type exhibited by liquids which freeze from "liquid 
solutions" into what are known as "solid solutions/' which 
by aid of the microscope are found to be homogeneous mix- 
tures of crystals. On the other hand, alloys which lie to 
the right of UV, are of the type which form " eutectics." 
This will be described later. This dividing line UV, which 
occurs at about 1.7% of carbon, divides the iron-carbon 
alloys into these two natural divisions. It was the basis 
for calling those having 2% of carbon or less, "steels," and 
those with over this amount, "cast irons." 

Molten iron is so greedy for carbon, that, when it can get 
it, it readily holds in solution from 7% to 10% of this ele- 
ment. But solid (frozen) iron cannot retain anything like 
this amount. As we learned in the last chapter, gamma 
iron is the only variety which can exist above our lines of 
loss of conductivity, magnetism and recalescence, i. e., Ar 3 , 
Ar 3 . 2 , etc. It is, too, the only variety of solid iron which 
is able to retain carbon in solution, and it can retain only 
about 1.7% of it. 

So when molten steel containing 1.5% of carbon, say, 
cools until it reaches the temperature represented by the 
line, AB, which, at its intersection with the 1.5% carbon 
line would be at about 2582° F., particles or crystals begin 
to freeze out and float in the molten alloy. As the tempera- 
ture falls, more crystals separate until, when the tempera- 
ture determined by intersection of the 1.5% carbon line with 
the lower freezing curve, AE, is reached, the last of the 
now mushy alloy solidifies. 

Alloys of all other compositions below 1.7% of carbon do 
just this way except that the temperatures at which freez- 
ing begins and ends are different and distinctive for each 



EQUILIBRIUM DIAGRAM OF IRON-CARBON ALLOYS 339 

composition.* Upon freezing, every one of them retains in 
"solid solution" in the "gamma" iron whatever carbon it 
had in the liquid or molten solution. But, as stated above, 
it can not be over the 1.7% limit. 

Of the iron-carbon alloys of compositions lying to the 
right of the line UV, we find the case to be different, for 
each one of them has more than the 1.7% of carbon which 
is the maximum amount which "gamma" iron can retain. 
Now the lowest temperature at which any iron-carbon al- 
loy can exist without freezing is slightly above 2066° F., 
and there is but one composition — 95.7% of iron and 4.3% 
of carbon — which can survive until this low temperature is 
reached. A content of 4.3% of carbon then, is the greatest 
and also the least concentration which Nature will allow 
to remain molten clown to this minimum temperature. This 
4.3% carbon composition which is the lowest melting, i.e., 
the easiest melted alloy, is called the "eutectic" alloy from 
Greek words which mean "well melting." This eutectic 
composition may be said to divide or rather subdivide this 
group of alloys into two groups, those containing between 
1.7% and 4.3% of carbon, and those which have 4.3% and 
over. 

As stated before, freezing is not an instantaneous but a 
progressive process. During the freezing period of any 
of these alloys which have over 1.7% of carbon the still 
liquid portion which remains after freezing begins to be- 
come smaller and smaller in quantity as freezing progresses 
just as it did in alloys of the "solid solution" group. And 
as Nature allows a concentration of 4.3% of carbon as the 
highest concentration at the minimum temperature the very 
last of the remaining liquid of every alloy eventually gets 

* Temperatures of beginning and end of freezing may always be ascertained 
by locating on the freezing-point diagram the points at which the vertical line 
representing the desired composition intersects and crosses the lines of the freez- 
ing-point curves — in these cases, AB and AE. 



340 NON-TECHNICAL CHATS ON IRON AND STEEL 

to this eutectic composition just before the alloy freezes. 
Those to the left of the eutectic or exact 4.3% composition 
do so by the gradual freezing out of iron containing the 
maximum or 1.7% of carbon, i.e., iron is taken out faster 
than carbon, hence there is gradual concentration of car- 
bon in the remaining liquid. This goes on until 4.3% is 
reached. The compositions to the right of the line WX 
throw out the chemical compound, Fe 3 C, which contains 
6.6% of carbon, whereby carbon is eliminated faster than 
iron and the desired 4.3% carbon alloy is arrived at from 
the other direction. 

To illustrate, take, say, the composition represented by 
the vertical line at 3% carbon and 97% iron. As the mol- 
ten alloy cools it reaches the temperature 2330° F., at which 
temperature the vertical line representing the 3% carbon 
composition cuts the line AB. Here the alloy begins to 
freeze by the separation of small crystals of solidifying iron 
containing definite amounts of carbon.* But as the carbon 
thus taken along by the freezing crystals of iron is always 
less than 1.7%, a proportionally greater amount of iron 
than carbon is removed from the unfrozen part of the al- 
loy and the remaining liquid or unfrozen part, therefore, 
is left with slightly more than the 3% of carbon with 
which it started. 

This we must now consider another alloy with a lower 
freezing point, the reason being, of course, its higher car- 
bon content. At the next lower temperature, more iron 
containing carbon is frozen out and the remaining liquid 
is again left a little higher in carbon than before. In this 
way the continually diminishing amount of remaining liquid 
keeps concentrating, forming thereby a continuous succes- 

* The percentages of carbon carried by the particles of iron freezing at any 
particular temperature of the solidification range may be determined trom the 
diagram but the works named in the reference list should be consulted for 
method and explanation. 



EQUILIBRIUM DIAGRAM OF IRON-CARBON ALLOYS 341 



sion of alloys of higher and higher carbon content as the 
temperature continuously drops. 

Eventually, of course, the concentration of this remain- 
ing liquor becomes 4.3% of carbon just before completion 
of the freezing at 2066° F. 

Now with alloys containing more than 4.3% of carbon, 
almost the opposite occurs. Let us choose the one having 
5% carbon and 95% of iron. This molten alloy cools un- 
til at 2215° F., 
small crystals 
begin to freeze 
and form in the 
molten mass. 
But, as the 
liquid already 
has more than 
the favored 
4.3% of carbon, 
it is not free iron 
which freezes 
out, but instead, 
the chemical 
compound, Fe 3 C, 
which contains 
6.6% of carbon. This, of course, takes out carbon pro- 
portionally faster than iron, hence, at each very slightly 
lower temperature, the liquid which remains unfrozen con- 
tains just a little less of carbon than did its predecessor. 
So the constantly decreasing amount of remaining liquid 
progresses through a succession of compositions each con- 
taining just a little less of carbon than the previous one, 
and eventually, just before freezing we get back to the mix- 
ture which contains 4.3% of carbon. Of course there is 
left unfrozen by this time only a very small amount 




The "Eutectic," the Part of the Allot Which 

Solidifies Last 

(Magnification 700 Diameters) 



342 NON-TECHNICAL CHATS ON IRON AND STEEL 

of the alloy and it is this which has the composition 
stated. 

The "Eutectic" 

Now, having just the composition which she wants, 
whether arrived at from alloys lower or higher than 4.3% 
in carbon, Nature lets this composition freeze at once in 
thin alternating plates which lie side by side about and 
among the earlier frozen crystals of the alloy. The ap- 
pearance of this typical eutectic formation under the micro- 
scope is shown on page 341. 

Had we chosen the 4.3% alloy itself, neither any of the 
solid solution of carbon in iron nor the chemical compound, 
Fe 3 C, would have frozen out, but the whole mass would 
have remained liquid down to 2066° F., where the whole 
would have solidified at once in the plate-like eutectic for- 
mation just described. 

To sum up, iron-carbon alloys which contain less than 
1.7% of carbon, in other words, the steels, freeze as solid 
solutions of carbon in gamma iron. This, of course, is the 
metallographic constituent which is called austenite. It 
is not of a definite composition as it contains whatever car- 
bon is available up to 1.7%. Alloys containing between 
1.7% and 4.3% of carbon gradually freeze out this solid 
solution, austenite, more and more being formed in the 
freezing alloy until, upon arriving at a concentration of 
4.3% of carbon for the remaining liquid, the latter, too, 
freezes as a eutectic of alternating plates of more of this 
same constituent, austenite, and the carbide of iron, Fe 3 C, 
about and among the crystals of the previously formed 
austenite. From alloys which contain more than 4.3% 
of carbon, iron carbide, Fe 3 C, gradually freezes out 
as the temperature falls, until, at concentration of 4.3% 
of carbon, the eutectic of remaining carbide and austen- 



EQUILIBRIUM DIAGRAM OF IRON-CARBON ALLOYS 343 

ite forms about and among the earlier-frozen carbide 
crystals, always at the same temperature, 2066° F., no 
matter what the original composition of the al- 
loy. 

Upon reheating, the constituents melt in reverse order, 
the eutectic liquifying first at 2066° F., the remainder of 
the alloy gradually becoming liquid between this tempera- 
ture and the temperature at which the first freezing began 
during cooling. 

Transformations and Decompositions 

So far we have considered only the freezing of the iron- 
carbon alloys from the molten to the solid condition. Now 
what happens to them at temperatures below 2066° F.? Do 
they remain as we left them above, until and after they 
are fully cold! 

We must now combine the little sketch which we made on 
page 319, by plotting the points, Ar l7 Ar 2 and Ar 3 , with 
the freezing point diagram which we have just now been 
considering. You remember that we found all sorts of 
things happening to our 0% to 1.7% alloys — the steels — 
at temperatures around 1290° F., 1395° F., and 1650° F. 
Similarly, a great deal happens to these other alloys, as 
they cool from their solidifying temperatures downward. 

But for the moment considering only the steels, i.e., the 
third of the diagram to the left of the 1.7% carbon line, 
we remember that upon completion of the solidification of 
any alloy, we had only a frozen solution of all the carbon in 
iron. Now in the bottom part of this left third of our dia- 
gram on page 344, the line GOSE does not look so very 
much different than the freezing line, ABC, does it? It 
resembles it not only in appearance but also in actual ex- 
perience. But in this case it represents not a freezing from 
liquid to solid but a decomposition, or better perhaps, a 



344 NON-TECHNICAL CHATS ON IRON AND STEEL 



transformation. The solid solutions or alloys which con- 
tain less than .9% of carbon give up their excess of pure 
iron upon getting clown to temperatures lying along the 
line GOS, by gradual decomposition of the austenite. In 
alloys lying to the right of this .9% carbon vertical line 

£cjui/ibrmm Diagram of /ron-Cqrbon A//oys. 

w 




/Zoo 



IOOO' 



Carbon OZ 
Iron 100% 

TV X 

The Freezing-Point and Critical-Point Curves Make up the Equilibrium 

Diagram 

the austenite rids itself of excess carbon by throwing out 
of solid solution and freeing the chemical compound, Fe 3 C, 
as the line SE is reached and passed. That is, analogously 
to what occurred during freezing, certain concentrations 
occur in the solid, lower carbon alloys by gradual rejection 
of pure iron crystals until the remainder of the mass has 
exactly .9% of carbon, or deconcentrate in the higher 



EQUILIBRIUM DIAGRAM OF IRON-CARBON ALLOYS 345 

ones by rejection of Fe 3 C until they reduce the carbon 
to this .9% figure. In all cases, by the time the temperature 
1290° F., has been reached this has been accomplished and 
the remaining undecomposed austenite, now with just .9% 

Equilibrium Diagram of Iron- Carbon A//ous 



tenife crystals 
and liquid 




Ausfenite a Ad £ufecfic 



/ooo' - 



('With Sitic. 
Cementr, 
or Fer/ite, 
or F err lie 



\Liquid 



Cementite crystals 
and liquid , 



ftr 



Free\zmS 

! . 



/ With Siliton \and s/oW\ 
\coolmq Grqphi\e forms j 



ends 



Cemeqtife and Eut\ectic 
I I 



Carbon of. 
Iron loofi 

T 



Pear lite ' and Cem en h te. 
on and Slow Coqlinc/ — , 
e, Pear lite anq Gtophite~\ \ 
Pear lite and\ OrJph,te [depending 

. . -i i upon conditic 

and Graphite \ ) r 



97% 



96% 



57. 
95% 



6% 6.57. 
94% 93.5% 



The Equilibrium Diagram and Interpretation as Now Tentatively Accepted 



of carbon, in some way splits into the alternating plate-like 
constituent which is shown in the cut on page 341. 

This plate-like constituent we can hardly call eutectic 
or "well-melting" alloy for it, as well as the rest of the 
alloy, has been solid for a long time. But being so similar 



346 NON-TECHNICAL CHATS ON IRON AND STEEL 

in derivation and appearance to the euteetic which forms 
during freezing of a molten alloy, it is proposed that it be 
called the next best thing, the "eutectoid." It is often 
called the euteetic, however. 

By this time you doubtless have seen that the free iron 
which was thrown out of the steel having less than .9% 
carbon is the ferrite which we found in the soft steels, and 
that the chemical compound, Fe 3 C, of the higher carbon 
steels is the extremely hard constituent, cementite. The 
eutectoid or plate-like structure is, of course, pearlite, which 
in the last chapter we found to consist of just these alter- 
nating plates of ferrite and cementite. 

The Cast Irons 

All of the alloys lying to the right of the line UV con- 
tain more than 1.7% of carbon, and, according to our classi- 
fication, therefore, are "cast irons." 

We have seen how they freeze either as euteetic alone, 
as crystals of austenite with euteetic or as crystals of ce- 
mentite (Fe 3 C) and euteetic, depending upon the original 
composition of the molten alloy. At and just below the 
temperatures represented by the line ED, this undoubtedly 
represents the situation. 

What happens to the alloys from this temperature down 
to normal depends upon conditions. Just what occurs and 
the mechanism of it is not definitely known except in the 
practical way. Certain it is, the "precipitation" of free 
carbon is necessary for cast irons which are to be service- 
able for usual purposes. This may occur with consequent 
softening during the first cooling or they may be cast as 
"hard iron" and softened afterward. 

In Chapter XI we said that silicon was a "softener" as 
its presence brought about precipitation of the carbon as 
graphite throughout the cast iron, thereby softening it both 



EQUILIBEIUM DIAGRAM OF IRON-CARBON ALLOYS 347 

by reason of the presence of the soft flakes of graphite and 
because it leaves so little of the carbon in the "combined" 
or hardening condition. So silicon is a ready means of 
bringing about decomposition of the higher temperature 
structures as the alloys cool. 

The speed of the cooling also exerts a very powerful in- 
fluence in determining the amount of graphite which will 
separate. Other conditions being equal, the slower the cool- 
ing, the greater the decomposition with resulting graphite. 
Swift cooling, even such as results from the dumping of 
castings from the molds while at nearly white or high red 
heat results in insufficient graphite and otherwise harder 
metal. Cooling of very hot castings on a cold floor or in a 
current of cool air has considerable hardening effect even 
when the composition of the alloy would otherwise give 
very soft and machinable metal. In an extreme and very 
interesting case a few very hard cast iron flanges were each 
day found among the many thousands of habitually soft 
castings regularly produced. Each day two or three ex- 
pensive "taps" were ruined by attempting the impossible 
— the machining of these pieces of hardened iron, which, on 
the outside, looked just like all the rest. It was soon dis- 
covered that two or three mold dumpers each noon and 
evening were warming water for "wash-up" by dropping 
into the pails a flange or two which were still white-hot 
after dumping from the molds. The men were innocent of 
any intention of harm but their warm water cost several 
hundred dollars before their method of producing it was 
discovered. 

Silicon and rate of cooling are the two most powerful 
influences but presence of certain elements other than sili- 
con also influences to some extent the degree of hardness. 
However, while silicon has a strong softening effect, man- 
ganese and sulphur have an opposite or hardening ten- 



348 NON-TECHNICAL CHATS ON IRON AND STEEL 



dency. On this account the amounts of these latter ele- 
ments which can be used or allowed must be strictly limited. 
From the above it is seen that all sorts of cast iron can 
be produced ranging from the extremely hard, high cemen- 
tite, white irons with low silicon content down to the very 
soft gray irons which result mainly because of higher sili- 
con content and slower cooling. 

The white irons are more or less unstable as is shown 
by the decomposition through which the hard, white iron 

castings become "mal- 
leable" by annealing 
as was told in Chapter 
XII which discussed 
Malleable Cast Iron. 

The gray cast irons 
are much more stable. 
They consist of what, 
in an early chapter, 
we referred to as 
' ' steels with an impur- 
ity, the graphite 
flakes." They consist, 
then, of free, soft iron 
or ferrite, certain amounts of the characteristic steel con- 
stituent, pearlite, and the soft graphite flakes. 

They arrive at this composition, through breaking down 
of the austenite and cementite structures during the cool- 
ing, — just how not having been satisfactorily determined. 
Consistent study is being put upon this subject and several 
unique and long-studied possible explanations of this sec- 
tion of the full equilibrium diagram have been proposed 
and debated, all based upon the data so far available. While 
much information on this subject has been gained the mat- 
ter is still so much in dispute that it is best for us to venture 




No. 31. Gray Cast Iron with Ferrite, Pearl- 
ite and Graphite Flakes 
(Magnification 10 Diameters) 



EQUILIBRIUM DIAGRAM OF IRON-CARBON ALLOYS 349 

nothing definite in regard to just how the changes occur. 
The reference books for this chapter (see page 354) give 
quite completely the data, theories and explanations so far 
available. 

Compared with the steels, the cast irons are vastly com- 
plicated. In them we have elements which occur in prac- 
tically negligible amounts in the steels. Commercial cast 
irons, for instance, have silicon ranging anywhere from 
1/2% to 3%, phosphorus .10% to 2%, graphite 0% to 3.50%, 
and carbon in the combined form (pearlite or cementite) 
from 3.50% to .10%. If these represent the majority of 
cast irons what about our pig irons which have 2, 5, 8, 10 
or even 15% of silicon, others with 1 or 2 and occasionally 
very much more of manganese, and still others which vary 
widely in phosphorus content? — for from the metallo- 
graphic and physical chemistry standpoint pig irons are 
cast irons. 

As we can never get perfectly pure iron-carbon alloys 
to experiment with, their content of other elements, silicon, 
nickel, phosphorus, etc., vitiate more or less the results ob- 
tained, but even could such pure alloys be secured we are 
not greatly helped since our serviceable alloys are never 
such. Each added element brings about greater complica- 
tion and one does not wonder that in the short twenty 
years which have elapsed since study was seriously under- 
taken, metallurgical science has not entirely solved the 
big problem. 



REFERENCES 



GENERAL & VARIOUS 

"The A B C of Iron and Steel," Penton Publishing Co., Cleveland. 

"The Steel Foundry," J. H. Hall, McGraw-Hill Book .Co., New 
York. 

"The Metallurgy of Steel," H. M. Howe, The Scientific Publishing 
Co., New York. 

' ' The Manufacture and Properties of Iron and Steel, " H. H. Camp- 
bell, Hill Publishing Co., New York. 

"The Metallurgy of Iron and Steel," B. Stoughton, McGraw-Hill 
Book Co., New York. 

"The Metallurgy of Steel," Harbord and Hall, Charles Griffin & 
Co., Ltd., London. 

"Liquid Steel," E. G. Carnegie, Longmans, Green & Co., London. 

"Krupp's Steel Works," F. C. G. Muller, Wm. Heinemann, Lon- 
don. 

"By Bread Alone" (a novel), I. K. Friedman, McClure, Phillips 
& Co., New York. 

CHAPTER I 

"The History of the Manufacture of Iron in All Ages," James 
Swank, Am. Iron and Steel Assoc, Philadelphia, Pa. 

"The Materials of Engineering — Iron and Steel," Robert Thur- 
ston, John Wiley & Son, New York. 

CHAPTER II 

' ' The Honorable Peter White, " R. D. Williams, Penton Publishing 
Co., Cleveland, 0. 

350 



REFERENCES 351 

"The Iron Ore Resources of the World," International Geological 
Society, Stockholm, 1910. 

"The Story of Coal and Iron in Alabama," Ethel Armes, Cham- 
ber of Commerce, Birmingham, Ala. 

CHAPTER III 

"Modern Coking Practice," T. H. Byrom, C. Lockwood & Son, 
London. 

"Coal and Coke," Frederick H. Wagner (1916), McGraw-Hill 
Book Co., New York. 

"Washing and Coking Tests of Coal," A. W. Belden, G. R. Dela- 
mater, J. W. Groves, Bulletin 368, U. S. Geological Survey, 
1909. 

"Washing and Coking Tests of Coal and Cupola Tests of Coke," 
R. Moldenke, A. W. Belden, and G. R. Delamater, U. S. Fuel 
Testing Plant, St. Louis, Mo., U. S. Geological Survey, Bulle- 
tin 336, 1908. 

"Manufacture of Coke and Other Prepared Fuels and the Saving 
of By-Products, ' ' John Fulton, 1905, International Text Book 
Co., Pittsburg, Pa. 

CHAPTER IV 

"The Blast Furnace and Manufacture of Pig Iron," Robert For- 

sythe, D. Williams & Co., New York. 
"A Study of the Blast Furnace," Harbison- Walker Refractories 

Co., Pittsburg, Pa. 
"The Principles of Manufacture of Iron and Steel," Sir I. L. Bell, 

George Routledge & Son, London. 

CHAPTER VI 

"The Business Message of the Wrought Iron Bar," Interstate Iron 

and Steel Co., Chicago. 
"The Control of Quality in Every Process," A. M. Byers Co., 

Pittsburg, Pa. 

CHAPTER VII 

' ' The Cementation of Iron and Steel, ' ' Gioletti, McGraw-Hill Book 
Co., New York. 



352 NON-TECHNICAL CHATS ON IRON AND STEEL 

"The Fine Steel Industry," J. A. Mathews, The Halcomb Steel 
Co., Syracuse, New York. 

CHAPTER VIII 

"Sir Henry Bessemer — An Autobiography," Offices of Engineer- 
ing, London. 

"The Romance of Iron and Steel — The Story of a Thousand Mil- 
lionaires," H. N. Casson, Munsey's Magazine, April, 1906, 
and on; In book form, A. S. Barnes & Co., New York. 

CHAPTER IX 

"The Manufacture of Open-Hearth Steel Castings," W. M. Carr, 

Penton Publishing Co., Cleveland. 
"The Basic Open-Hearth Steel Process," C. Dichmann, Constable 

& Co., Ltd., London. 
"A Study of the Open-Hearth," Harbison-Walker Refractories 

Co., Pittsburg, Pa. 

CHAPTERS X & XI 

"Cast Iron in the Light of Recent Research," W. H. Hatfield, 

Charles Griffin & Co., Ltd., London. 
"Cast Iron," W. J. Keep, John Wiley & Sons, New York. 
"The Metallurgy of Cast Iron," T. D. West, Cleveland Printing 

& Publishing Co., Cleveland, 0. 
"American Foundry Practice," T. D. West, John Wiley & Sons, 

New York. 

CHAPTER XII 

"The Production of Malleable Castings," Richard Moldenke, The 

Penton Publishing Co., Cleveland. 
"Malleable Cast Iron," S. J. Parsons, A. Constable & Co., Ltd., 
London. 

CHAPTER XIII 

"Electric Furnaces in the Iron and Steel Industry," Rodenhauser 
& Schoenawa (Translated by Vom Baur), John Wiley & Sons, 
New York. 



REFERENCES 353 

"The Electric Furnace," A. Stansfield, The McGraw-Hill Book 

Co., New York. 
"Electric Furnaces for Making Iron and Steel," Lyon and Keeney, 

U. S. Bureau of Mines, Bulletin No. 67 (1914). 

CHAPTERS XIV & XV 

"The Manufacture and Uses of Alloy Steels," H. D. Hibbard, U. S. 

Bureau of Mines, Bulletin No. 100 (1915). 
"High Speed Steel," 0. M. Becker, McGraw-Hill Book Co., New 

York. 
"Nickel Steel — Its Practical Development in the United States," 

H. F. J. Porter, Gassier 's Magazine, 1902, Page 480. 
"Chrome-Vanadium Steel," W. E. Gibbs, Cassier's Magazine, June, 

1910, Page 174. 
"Vanadium Steels," J. Kent Smith, American Vanadium Co., 

Pittsburgh, Pa. 
"Alloy Steels in Motor Car Construction," J. A. Mathews, Jour- 
nal Franklin Institute, May, 1909, Page 379. 
"On the Art of Cutting Metals," F. W. Taylor, Trans. Am. Soc. 

Mech. Eng. 1906—28 No. 3. 
' ' High Speed and Carbon Tool Steels, ' ' Machinery Eeference Series 

No. 117, Industrial Press, New York. 
"Alloy Steels," Machinery Reference Series No. 118. 

CHAPTER XVI 

"Drop Forging, Die Sinking and Machine Forging of Tools of 
Steel," J. V. Woodworth, N. W. Henley Publishing Co., New 
York. 

"Metal Working," Hasluck, David McKay, 1907. 

"Drop Forging," Machinery's Reference Series No. 45. 

"Press Working of Metals," Oberlin Smith, John Wiley & Sons 
(1913). 

CHAPTER XVII 

"The Rolling Mill Industry, F. Kindl, Penton Publishing Co., 
Cleveland, Ohio. 



354 NON-TECHNICAL CHATS ON IRON AND STEEL 

CHAPTERS XVIII & XIX 

"Wire Manufacture and Uses," J. B. Smith, John Wiley & Sons, 
New York. 

CHAPTERS XX & XXI 

"Modern Welded Pipe," National Tube Co., Pittsburg, Pa. 

"The Control of Quality in Every Process," A. M. Byers Co., 
Pittsburg, Pa. 

"Seamless Tubing, Bulletin No. 17- A, National Tube Co., Pitts- 
burg, Pa. 

"The Manufacture of Iron and Steel Tubes," E. C. R. Marks, 
Van Ostrand & Co., New York. 

CHAPTERS XXII & XXIII 

" The Metallography of Steel and Cast Iron," H. M. Howe, Mc- 
Graw-Hill Book Co., New York. 

"The Metallography and Heat Treatment of Iron and Steel,' 
Albert Sauveur, Sauveur and BoylstOn, Cambridge, Mass. 

"Metallic Alloys: Their Structure and Constitution," G. H. Gul- 
liver, Charles Griffen & Co., Ltd., London. 



INDEX 



Acid linings for furnaces, 139, 156 

Allotropic modifications of iron, 322 

Alloy steels, 232 

Ammonia from coke ovens, 49 

Analysis, chemical, 165 

Annealing malleable cast iron, 203 

cast steel, 220 

tool steels, 109, 233, 333 

tubes, 307 

wire, 285 

Bar, Merchant, 154 

muck, 99 
Basic linings for furnaces, 139, 156, 

230 
Beehive charcoal, 38 

coke, 44 
Benzol, 49 
Bessemer, Sir Henry, 123 

steel, 123, 226 
Black heart malleable iron, 209 
Blast, 1, 11, 52, 58, 172 
Blast furnace, 9, 10, 52 
Blister steel, 117 

Blowing of Bessemer steel, 128, 225 
Boyden, Seth, 196 
Busheled iron, 105 
Butt-welded pipe, 293 
By-products, 42, 47 

Carbon, effect of, on iron, 8, 74, 83, 
86, 109, 116, 180, 198, 233, 319, 337 

effect of, on iron ore, 4, 57 
Cast iron. See Iron, cast 
Castings, 189 

of cast iron, 178 



Castings of malleable iron, 197 

of pig iron (direct castings), 80 

"rubber," 192 

of "semi-steel," 188 

of steel, 214 
Cementation steel process, 106, 112 
Charcoal, 7, 37, 95 

Chemical changes during refining, 7, 
97, 119, 128, 149, 155, 160, 201, 
230 
Chemistry of gas producers, 158 
Chromium in steel, 238, 243 
Cinder in wrought iron, 96, 97, 101, 

300 
Classification according to chemical 
analysis, 83 

of iron alloys, 69, 180 

metallographic, 70 

by physical test, 83, 188 

of steels, 107, 155 

volumetric, 88 
Coal, 41, 49 

Cold finishing of steel, 270, 306 
Coke, 11, 41 
Coke ovens, 44, 46 
Conductivity of steels, 315 
Converters, 126, 226 
Cooling curves of steels, 316 
Cort, Henry, 11, 95, 259 
Critical temperature or range in steels, 

315, 319 
Crucibles, 118 

Crucible steel process, 106, 118, 223 
Cupola melting process, 161, 171, 198 



Dilatation of steel, 315 



355 



356 



INDEX 



Dolomite, 50 

Drawing bench, 287, 306 

Drawing, effect of cold drawing, 248 

of tubes, 305 

of wire, 284 
Duplex steel process, 155 

Electric furnaces, 227 

Electric steel, 227 

Equilibrium diagram of iron-carbon 

alloys, 335, 345 
Eutectic, 342 
Eutectoid, 346 

Tiber of wrought iron, 92, 93, 101 

Fluor spar, 51 

Flux, 50, 173 

Forging, 248 

Freezing-point curves of iron-carbon 

alloys, 337 
Fuels, 6, 11, 15, 37, 94, 96, 119, 130, 

157, 170 
Furnaces, air, 398 

Bessemer converters, 123, 226 

Catalan, 7 

Cementation, 115 

Cupola, 171 

early types of, 6, 93 

electric, 227 

open-hearth, 142 

puddling, 95 

Siemens-Martin, 142 

Talbot, 153 

Gas, coke oven, 41, 47 
natural, 157 
producer, 157 

Hadfield, Sir Eobert, 235 
Hammers for forging, 249 
Hardening, air or self, 241 
Hardening of steels, 109, 233, 240, 

316, 333 
Holley, Alexander L., 127 



Huntsman crucible melting process, 
10, 118 

Ingots, steel, 245 

Irons, " black heart" malleable cast, 

209 
Busheled, 105 
east (See also Semi-steel), 7, 79, 

160, 178, 346 
classification of, 69, 89 
early history of, 1, 4, 91 
ingot, 75 
malleable, 4, 123 
malleable cast, 81, 195, 
pig, 63 

puddled, 75, 91 
strengths of the iron alloys, S3, 

188 
Swedish, 93 
white, 81, 184, 198 
"white heart" malleable cast, 21 
wrought, 75, 77, 91 
wrought, early processes for, 4, 93 

Kelly, William, 124 

Lap-welded pipe, 296 
Lime, use of, 139, 149, 230 
Limestone as flux, 50, 173 
Linings, acid and basic, 139, 156, 230 

of Bessemer converters, 139 

of electric furnaces, 230 

of open-hearth furnaces, 148 

of puddling furnaces, 97 

Magnetism, loss of, in steels, 314 
Manganese, 135, 151 

Hadfield 's manganese steel, 235 
Mannesmann process for billet pierc- 
ing, 302 
Melting-points of iron-carbon alloys, 

4, 6, 83, 94, .142 
Metallography, 70, 180, 324 
Metalloids, 86, 89, 128 



INDEX 



357 



Mills. See Boiling mills 

Mixer, 131, 153 

Molds and Molding, 13, 189, 218 

Muck bar, 99 

Mushet, Robert F., 135, 240 

Nasmyth, James, 251 
Nickel "in steel, 237 

Open-hearth steel process, 142, 223 
Ore, iron, 3, 17, 53, 144 

Mesaba, 26 

unloaders, 31 

use of (iron-oxide), in refining 
processes, 97, 149, 230 

Phosphorus in iron and steel, 97, 139, 

144, 152, 230 
Pickling of steel, 285, 305 
Piercing of steel billets for tubes, 302 
Pig bed, 61 
Pig iron, 63 

castings ("direct castings"), 80 
Pipes and tubes, early, 292 
Pipes, butt-welded, 293 

lap-welded, 296 

in steel ingots, 245 
Plates, making of steel, 264 
Press, forging by hydraulic, 256 
Puddling of iron, 97 

Rails, rolling of, 138, 273 

Reaumur, 115, 195 

Recalescence, 311, 316 

Recarburization, 135, 151 

References, 350 

Regenerative system of heating, 146 

Risers on steel castings, 219 

Rods, rolling of, 277 

Rolling mills, 259, 277, 294, 304 

Rolling of muck bar, 99 

of rails, 138, 273 

of rods, 277 



Rolling of skelp for pipe, 293 

of steel plates, 264, 268 
Rolling vs. forging of steel, 258 

Segregation in steel ingots, 246 
"Semi-steel," 78, 185 
Sheets, rolling of, 273 
Siemens-Martin steel process. See 

Open-hearth 
Silicon in iron-carbon alloys, 83, 120, 

133, 168, 182, 346 
Skelp for pipe, 293 
Slag and cinder, 56, 58, 96, 97, 151 
Spiegeleisen addition in Bessemer 

process, 135 
Squeezer for puddled iron, 99 
Steam hammer for forging, 251 
Steels, acid, 139, 156 

alloy, 107, 232 

annealing of, 109, 220, 233, 285, 
307, 333 

basic, 139, 156, 230 

Bessemer process, 123, 154, 226 

blister, 117 

carbon, 107 

castings. See Castings of steel 

cementation, 106, 112 

chrome, 238 

classification of, 107, 155 

crucible, 106, 118, 223 

duplex, 155 

electric, 227 

hardening of, 109, 233, 240, 241, 
316, 333 

high-speed, 107, 240 

manganese, 235 

nickel, 237 

open-hearth, 107, 142, 223 

place in the iron family, 78 

"semi-steel," 79, 185 

shear, 118 

structures, decompositions and 
transformations of, 310, 337, 343 

tool, 107, 240 



358 INDEX 

Steels, tungsten, 236, 243 Tool steels, carbon, 107 
Wootz, Damascus, Toledo, etc., 8, high-speed, 107, 240 

121 Tubes and tube making, 302 

Strengths of iron-carbon alloys, 83, Tungsten in steel, 236, 241 
188 

of steel plate, 270 Uses of irons and steels, 71, 83, 184, 
of wire, 290 212, 213, 215, 249 

Structures of the irons and steels, 310, 

323, 337, 343 Vanadium in steel, 235, 243 
See also Metallography 

Sulphur in fuels and alloys, 40, 43, 95, Welding rolls, 297 

97, 155, 168, 203, 230 Welding of steel, 83, 294, 296 

"White heart" malleable cast iron, 
Tar, coal, 48 210 

Taylor, Frederick W., 241 White iron, 81, 184, 198 

Tempering of steels, 109, 240, 331 White, Maunseh 241 

Titanium in steel, 234 Wire, drawing of, 284 

Tools, 3, 107, 212 Wootz steel process, 8, 121 



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